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<h1><a id="title" name="title" />W3C XML Schema Definition Language (XSD): Component Designators</h1>
<h2><a id="w3c-doctype" name="w3c-doctype" />W3C Candidate Recommendation 19 January 2010</h2><dl><dt>This version:</dt><dd>
     <a href="http://www.w3.org/TR/2010/CR-xmlschema-ref-20100119/">http://www.w3.org/TR/2010/CR-xmlschema-ref-20100119/</a>
   </dd><dt>Latest version:</dt><dd>
     <a href="http://www.w3.org/TR/xmlschema-ref/">http://www.w3.org/TR/xmlschema-ref/</a>
   </dd><dt>Previous versions:</dt><dd>
     <a href="http://www.w3.org/TR/2008/WD-xmlschema-ref-20081117/">http://www.w3.org/TR/2008/WD-xmlschema-ref-20081117/</a>
     <a href="http://www.w3.org/TR/2008/WD-xmlschema-ref-20080910/">http://www.w3.org/TR/2008/WD-xmlschema-ref-20080910/</a>
     <a href="http://www.w3.org/TR/2005/WD-xmlschema-ref-20050329/">http://www.w3.org/TR/2005/WD-xmlschema-ref-20050329/</a>
     <a href="http://www.w3.org/TR/2004/WD-xmlschema-ref-20040716/">http://www.w3.org/TR/2004/WD-xmlschema-ref-20040716/</a>
     <a href="http://www.w3.org/TR/2004/WD-xmlschema-ref-20040309/">http://www.w3.org/TR/2004/WD-xmlschema-ref-20040309/</a>
     <a href="http://www.w3.org/TR/2003/WD-xmlschema-ref-20030109/">http://www.w3.org/TR/2003/WD-xmlschema-ref-20030109/</a>
   </dd><dt>Editors:</dt><dd>Mary Holstege, Mark Logic Corporation</dd><dd>Asir S. Vedamuthu, webMethods (until May 2005)</dd></dl><p>This document is also available in these non-normative formats: <a href="scds.xml">XML</a>.</p><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2010 <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.org/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p></div><hr /><div>
<h2><a id="abstract" name="abstract" />Abstract</h2><p>XML Schema: Component Designators defines a scheme for identifying XML
Schema components as specified by
<a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/">XML Schema Part 1: Structures</a> and
<a href="http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/">XML Schema Part 2: Datatypes</a>.
</p></div><div>
<h2><a id="status" name="status" />Status of this Document</h2><p><em>This section describes the status of this document at the
      time of its publication. Other documents may supersede this document.
      A list of current W3C publications and the latest revision of this
      technical report can be found in the
      <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
      http://www.w3.org/TR/.</em></p><p>
<span>
This W3C Candidate Recommendation specified W3C XML Schema Definition Language
(XSD) Component Designators. It is here made available for review by W3C
members and the public. </span>
It has been
produced by the <a href="http://www.w3.org/XML/Schema">W3C XML Schema Working
Group</a> (WG) as part of the <a href="http://www.w3.org/XML/Activity">XML Activity</a>.
It incorporates all Working Group decisions through
2008-10-31.
It has been reviewed by the Working Group and the Working Group has agreed to
publication as a Last Call Working Draft.
 </p><p>
The <span>Candidate Recommendation</span> review period for this document extends until <span>1 March 2010</span>.
    Comments on this document should be made in
    W3C's public installation of Bugzilla, specifying "XML Schema" as the
    product. Instructions can be found at <a href="http://www.w3.org/XML/2006/01/public-bugzilla">http://www.w3.org/XML/2006/01/public-bugzilla</a>. If access to
    Bugzilla is not feasible, please send your comments to the W3C XML
    Schema comments mailing list, <a href="mailto:www-xml-schema-comments@w3.org">www-xml-schema-comments@w3.org</a>
    (<a href="http://lists.w3.org/Archives/Public/www-xml-schema-comments/">archive</a>).
    Each Bugzilla entry and email message should contain only one
    comment.</p><p>
Any feature mentioned as a "feature at risk" may be retained as is or dropped,
depending on the feedback received from readers, schema authors, schema users,
and implementors. The only feature at risk is support for axes and components
that are dependent on the XML Schema 1.1 component model rather than the
XML Schema 1.0 component model.
</p><p>Publication as a <span>Candidate Recommendation</span> does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or obsoleted
by other documents at any time. It is inappropriate to cite this document as
other than work in progress.</p><p>
The W3C XML Schema Working Group intends to request advancement of this
specification and publication as a Proposed Recommendation (possibly with
editorial changes, and possibly removing features identified as being at risk)
as soon after 1 March 2010 as the exit criteria for the current
phase have been met.
</p><p>
This specification does not define any criteria for conformance and relies on
other specifications to specify criteria for conformance of implementations.
Nevertheless a <a href="http://dev.w3.org/2009/xmlschema-ref-test-suite/">test suite</a> is under development that
identifies the set of canonical schema component paths that should be generated
for particular test schemas, and that relates certain non-canonical component
paths to the corresponding canonical schema component paths.
</p><p>
The W3C XML Schema Working Group has agreed on the following specific CR exit criteria:
</p><ul><li><p>A test suite is available which provides cases for each
axis and component
type, both for the XML Schema 1.0 component model and the XML Schema 1.1
component model.</p></li><li><p>Generation or interpretation of canonical schema component
paths have been
implemented successfully by at least two independent implementations.</p></li><li><p>Generation or interpretation of each axis and component for
non-canonical
schema component paths has been implemented successfully by at least two
independent implementations.</p></li><li><p>The Working Group has responded formally to all issues
raised against this
document during the Candidate Recommendation period. </p></li></ul><p>At the time this Candidate Recommendation was published, no
interoperability or implementation report had yet been prepared.
</p><p>This document has been produced by the W3C XML Schema Working Group as part of
the W3C XML Activity. The authors of this document are the members
of the XML Schema Working Group.
</p><p>The following changes were made since the last public Working Draft:</p><ul><li><p>As resolution for issue <a href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=6450">6450</a>: make EBNF for Predicate more precise.</p></li><li><p>As resolution for issue <a href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=6451">6451</a>: clarify that predicate
counting starts at 1.</p></li><li><p>As resolution for issue <a href="http://www.w3.org/Bugs/Public/show_bug.cgi?id=6452">6452</a>: Make the rules such that
unprefixed axis names are in no null namespace and are reserved,
that the component kinds are part of a the namespace
"http://www.w3.org/2009/xmlschema-ref", and redefine
component-kind() to be returning expanded names.</p></li></ul><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
     2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/19482/status">public list of
     any patent disclosures</a> made in connection with the deliverables
    of the group; that page also includes instructions for disclosing a
    patent. An individual who has actual knowledge of a patent which the
    individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a> must disclose the information in accordance
     with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the W3C Patent Policy</a>.
   </p></div><div class="toc">
<h2><a id="contents" name="contents" />Table of Contents</h2><p class="toc">1 <a href="#section-introduction">Introduction (Non-Normative)</a><br />
2 <a href="#section-goals">Goals and Use Cases (Non-Normative)</a><br />
    2.1 <a href="#section-requirements">Requirements</a><br />
    2.2 <a href="#section-usecases">Use Cases</a><br />
3 <a href="#section-scds">Schema Component Designators</a><br />
    3.1 <a href="#section-scd-syntax">Schema Component Designator Syntax</a><br />
    3.2 <a href="#section-canonical">Canonical Schema Component Designators</a><br />
    3.3 <a href="#section-equality">Equality of Schema Component Designators</a><br />
4 <a href="#section-path">Schema Component Paths</a><br />
    4.1 <a href="#section-path-traversal">Schema Component Graph Traversal</a><br />
    4.2 <a href="#section-path-syntax">Schema Component Path Syntax</a><br />
    4.3 <a href="#section-path-interpret">Interpretation of Schema Component Paths</a><br />
    4.4 <a href="#section-axis">Schema Component Path Axes</a><br />
    4.5 <a href="#section-accessors">Accessors</a><br />
    4.6 <a href="#section-canonical-path">Canonical Schema Component Paths</a><br />
    4.7 <a href="#section-equality-path">Equality of Schema Component Paths</a><br />
5 <a href="#section-conformance">Conformance</a><br />
    5.1 <a href="#scp-conformance">Schema Component Path Conformance</a><br />
    5.2 <a href="#scds-conformance">Schema Component Designator Conformance</a><br />
    5.3 <a href="#N1136D">Extensibility</a><br />
6 <a href="#section-example">Examples (Non-Normative)</a><br />
    6.1 <a href="#section-primer-example">Extended Primer Example</a><br />
    6.2 <a href="#section-example-more">Additional Examples</a><br />
    6.3 <a href="#section-examples-abbreviations">Examples with component and elided-component Axes (Non-Normative)</a><br />
</p>
<h3><a id="appendices" name="appendices" />Appendices</h3><p class="toc">A <a href="#properties">Schema Component Properties (Non-Normative)</a><br />
B <a href="#axis-summary">Summary of Component Axes (Non-Normative)</a><br />
C <a href="#normative-glossary">Glossary (Non-Normative)</a><br />
D <a href="#references">References</a><br />
    D.1 <a href="#N11ED1">Normative References</a><br />
    D.2 <a href="#N11FE7">Non-normative Informational References</a><br />
</p></div><hr /><div class="body"><div class="div1">
<h2><a id="section-introduction" name="section-introduction" />1 Introduction (Non-Normative)</h2><p>This document defines a system for designating XML Schema components. Part 1
of the W3C XML Schema Definition Language (XSD) recommendation
<a href="#xsd1">[XSD1]</a> defines these
schema components.
<a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#concepts-data-model">Section 2.2</a>
lays out the inventory of schema components into
three classes:
</p><ul><li><p>Primary components: simple and complex type definitions, attribute
declarations, and element declarations</p></li><li><p>Secondary components: attribute and model group definitions,
identity-constraint definitions, and notation declarations</p></li><li><p>"Helper" components: annotations, model groups, particles, wildcards, and
attribute uses</p></li></ul><p>In addition there is a master schema component, the schema component
representing the schema as a whole. This component will be
referred to as the schema description component in this specification.
</p><p>Finally, there are schema components for the facets defined in Part 2 of the
W3C XML Schema Definition Language (XSD)
recommendation <a href="#xsd2">[XSD2]</a>:</p><ul><li><p><a href="http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/#rf-fund-facets">Fundamental Facets</a>: ordered, bounded, cardinality, numeric</p></li><li><p><a href="http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/#rf-facets">Constraining Facets</a>: whiteSpace, minInclusive, maxInclusive, minExclusive,
    maxExclusive, totalDigits, fractionDigits, length, minLength, maxLength,
    pattern, enumeration
</p></li></ul><p>Version 1.1 of the W3C XML Schema Definition Language (XSD)
recommendation
<a href="#xsd11_1">[XSD11_1]</a><a href="#xsd11_2">[XSD11_2]</a> adds additional components and
makes modifications to existing components, as well as introducing the notion
of "property records" to capture more complex structured values.
</p><p>At first blush, a QName (prefix:localname) may seem sufficient to the
task of designating any schema component.
This is not the case for various
reasons:
</p><ol class="enumar"><li><p>A QName is only meaningful in the context of particular namespace
bindings so that the QName can be resolved to a particular
<a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a>, i.e. a {namespace name, local name}
pair.
</p></li><li><p>The same <a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a> can be used in a particular schema to refer
to an
element declaration, an attribute declaration, a complex type or
simple type definition, a model group definition, an attribute group
definition, an identity constraint definition, and a notation declaration.
</p></li><li><p>Locally scoped element and attribute declarations cannot
necessarily be uniquely
named by an <a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a>.
</p></li><li><p>Anonymous type definitions have no
<a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a>, or they have an
<a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a> that
may vary with the
particular schema processor interpreting the schema.
</p></li><li><p>Certain schema components (annotation,
particle, wildcard) are invariably subordinate to
some other schema component, and
have no name of their own.</p></li><li><p>Certain schema components (attribute use and model group)
are subordinate to some other schema component, and any name they might be
construed to have is a reference to some other schema component (attribute
declaration and model group definition, respectively).
</p></li><li><p>The schema
description schema component has no name at all.</p></li></ol><p>A key technical challenge to obtaining a useful
system of naming XML Schema components is to address these issues or decide
that certain cases need not be addressed. In particular:
</p><ol class="enumar"><li><p>Designators must either include full <a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a>, or define
namespace bindings.</p></li><li><p>Designators must distinguish named components in
different symbol spaces from one another.</p></li><li><p>Designators must provide a means of distinguishing locally scoped
element and attribute declarations with the same name.</p></li><li><p>Designators must provide for any designatable unnamed components, such
as anonymous type definitions, wildcards, and the
schema
description
component.</p></li><li><p>Designators must function in the face of redefinitions.</p></li></ol><p>The schema description schema component may represent the amalgamation of
several distinct schema documents, or none at all. It may be associated with
any number of target namespaces, including none at all. It may have been
obtained for a particular schema assessment episode by de-referencing URIs given
in schemaLocation attributes, or by an association with the target namespace or
by some other application-specific means. In short, there are substantial
technical challenges to defining a reliable designator for the
schema description, particularly if that designator is expected to serve as a
starting point for the other components encompassed by that schema.
</p><p>This specification divides the problem of constructing schema component
designators into two parts: defining a designator for an assembled schema, and
defining a designator for a particular schema component or schema components,
understood relative to a designated schema. The first task
is discussed in <a href="#section-scds"><b>3 Schema Component Designators</b></a>, although this specification does
not define a specific rule for how to construct a single URI for an assembled
schema. The second task is addressed in detail
in <a href="#section-path"><b>4 Schema Component Paths</b></a>.
</p></div><div class="div1">
<h2><a id="section-goals" name="section-goals" />2 Goals and Use Cases (Non-Normative)</h2><div class="div2">
<h3><a id="section-requirements" name="section-requirements" />2.1 Requirements</h3><dl><dt class="label">Basic Functionality</dt><dd><ol class="enumar"><li><p>
  Each component should have at least one unambiguous designator
  that designates that component and no other.  However, certain
  abbreviation and wildcarding constructs may designate collections
  of components.
  </p></li><li><p>It should be possible to designate any schema component within a
  schema. However, some exceptions will be made for certain of the helper
  components.
  </p></li><li><p>Designators should provide (or assure) a URI for the unique identification of a schema.
  </p></li><li><p>If there is more than one designator for a construct, there should be
  exactly one canonical form of the designator.</p></li><li><p>Designators should be usable for either the XML Schema
  1.0 or the XML Schema 1.1 component model
  </p></li></ol></dd><dt class="label">Properties of the Designator</dt><dd><ol class="enumar"><li><p>Designators should be human-readable.</p></li><li><p>Given a designator, it should be possible to get the <a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a> for the
  designated component, if one exists for that component.
  </p></li><li><p>It should be possible to
   generate
  the canonical designator for each component
  algorithmically and consistently,
  either against an assembled
  schema or as the schema is assembled.</p></li><li><p>Designators should be parsable with compositional semantics (or, in
other words, they should have <em>expressive notation</em>).</p></li><li><p>There should be a formal specification of what constitutes a legal designator.</p></li></ol></dd><dt class="label">Compatibility</dt><dd><ol class="enumar"><li><p>Designators should be URI references.</p></li><li><p>Designators should work well in a RDDL environment.</p></li></ol></dd><dt class="label">Non-goals</dt><dd><ol class="enumar"><li><p>It is not a requirement to designate particle components as distinct
  from terms.</p></li><li><p>It is not a requirement that it be possible to
construct designators to refer to arbitrary schema components without any
knowledge of schema internals.</p></li><li><p>It is not a requirement to be able to tell, from a schema component
designator for an element declaration, whether instances of that element
declaration must appear in document instances with qualified or unqualified
names.</p></li><li><p>It is not a requirement that it be
  possible to uniquely assign schema
  component designators
  (element, attribute, and type designators) to information
  items in a document instance given only a set of schema component
  designators.
  </p></li></ol></dd></dl></div><div class="div2">
<h3><a id="section-usecases" name="section-usecases" />2.2 Use Cases</h3><dl><dt class="label">Type references</dt><dd><p>In general Schema Component Designators can be used to provide references to
arbitrary types, whether they are named global types or local or anonymous
types. These use cases all benefit from being able to refer to any type
declaration.</p><ul><li><p>Describing the type of an expression, where the type might be an
  anonymous or local type and a QName is therefore inadequate.
  There are a number of examples
  where this could be valuable in type-aware languages that operate on
  schema-validated XML:
  </p><ul><li><p>Naming the type of something that has been selected.
  </p></li><li><p>For use wherever types are named, for example to specify a type in
  a query expression.</p></li><li><p>Enabling interfaces like those described
  in <a href="#dom3">[DOM3]</a>
   to expose anonymous types.</p></li></ul></li><li><p>Identifying types for casting, specifically wrt anonymous
  and local types.</p></li><li><p>Identifying types for function signatures.
  </p></li></ul></dd><dt class="label">Element declaration references</dt><dd><p>These use cases benefit from being able to refer to any element declaration.
</p><ul><li><p>Referring to a local element declaration, with or without
  knowledge of the names of the scoping types and elements.
  </p></li></ul></dd><dt class="label">Stand-off schema annotation</dt><dd><p>Schema component designators can be used to refer to specific parts of a
schema to provide an out-of-band annotation capability, for commentary, error
reporting, or the association of layered semantics with schema components.
</p><ul><li><p>Writing error messages. There are two classes of error messages in
view: errors in an instance and errors in the schema. For example, if an
instance has a quantity which violates the constraints of a particular type,
such as a range constraint, it is valuable for the error message to be able to
name and refer to the specific type whose constraints were violated, even if
that is the anonymous type of a local element
declaration. An example of a schema
error would be that one type is not a valid restriction of another type.
This use case benefits from being able to name and refer to type, element, and
attribute declarations, as well as element and attribute uses, groups, and
possibly facets and particles. It is unclear whether being able to
refer separately
to particles versus groups is important. Being able to
refer separately
to attribute and element uses versus attribute and element declarations may be
important.
</p></li><li><p>Schema documentation. The transfer syntax for W3C XML Schema allows
  for documentation to be attached to components in-line. In many cases it may
  be preferable to keep the documentation separate from the active definitions,
  to save bandwidth, to provide for alternative documentation for different
  communities, and so on. Being able to refer to any schema component that can
  support an annotation (all but annotation itself) supports this use case.
  </p></li><li><p>Commentary on schemas, such as best practices documents, reviews and
  comparisons of particular schemas, and so on.
  </p></li><li><p>Associating an additional layer of semantics with schema
  components, for example, providing information to programming language or
  application environments to identify code to execute. For example, certain
  XML data binding frameworks today reference complex types and elements using
  their own path syntax for the purpose.
</p></li></ul></dd><dt class="label">Miscellaneous text-based uses within schema-based tools</dt><dd><p>Having a simple textual way to refer to the abstract components of a schema
enables certain kinds of text-based schema-related processing.</p><ul><li><p>A tool that creates interlinked HTML pages describing a schema.</p></li><li><p>String-based tests of type equivalence. Such tests can be used for
  comparing serialized PSVIs to provide for interoperable tests of type
  equivalence and processor comparisons.
  </p></li><li><p>String-based comparisons of processors generally, making it
  possible, for example, to ask and
  answer the question "Did two validations of the same document on
  different machines use the same type for a given element?"
   </p></li><li><p>input/output</p></li><li><p>user reports</p></li><li><p>glue/interfaces</p></li></ul></dd><dt class="label">Other</dt><dd><ul><li><p>Simple selection queries, such as "the type that is the base
  type of X" without knowledge of its name.</p></li><li><p>Creation or initial drafting of a new schema or schema document by
  selecting components from existing schema.
  </p></li><li><p>Using XSD simple types as the
  datatype of RDF literals.</p></li><li><p>Describing XSD Components
  within RDF, including
  the use of XSD simple types as RDF
  classes.</p></li><li><p>
Formal description requires unique identifier for each declaration and
definition component used within the context of the validation episode.
  </p></li><li><p>Enumerating dependencies among schema components. For example, where
  one complex type restricts another, the local elements in one depend on the
  local elements of the other.</p></li></ul></dd></dl></div></div><div class="div1">
<h2><a id="section-scds" name="section-scds" />3 Schema Component Designators</h2><p>Schema component designators rely on a layered model of schema
component reference. Schema component paths designate components in the context
of a particular schema assembly and depend on a namespace
binding context.
Full blown schema designators consist of two parts: a URI
without a fragment identifier part, which identifies the schema, and a
fragment identifier which encapsulates a schema component path to designate a
set of components in the context of that schema.

Schema component paths may be used in contexts other than
schema component designators, given appropriate specification of the namespace
binding context and the target schema.
</p><p>This section describes schema component designators as a whole. The details
of schema component paths are described in <a href="#section-path"><b>4 Schema Component Paths</b></a>.</p><p>[<a title="schema designator" id="key-sd" name="key-sd">Definition</a>: A <b>schema
designator</b> is a single URI for a resource representing an
assembled schema.]
</p><p>Many possible conventions for obtaining a single URI to refer to a schema
are possible.
In the simplest case, where there is one root schema document, the URI of
that document suffices. In other cases a schema may have been assembled from
multiple schema documents, or from components obtained via other
representations, and some
representation of that collection or of the assembled results will be required.
</p><p>We expect that it will be
highly desirable for the community to evolve one convention for referring
to an assembled schema to
ensure consistency of global schema component designators. This specification
declines to specify what that one way should be.
</p><div class="note"><p class="prefix"><b>Note:</b></p><p>
Like any resource, the schema denoted by a URI may be
represented in a variety of forms, with different media types.  When a URI is
dereferenced, the form and resolution of any fragment identifier depend (as
specified by <a href="#rfc3986">[RFC 3986]</a>) on the media type of the representation
obtained.
The representation of a resource obtained by dereferencing a schema URI
must therefore allow for the fragment identifier
syntax defined here in order for schema component
designators to successfully resolve to components.
Whatever representation of a schema is used,
the media type should allow for the fragment identifier syntax defined here.
This will be true for any XML representation of the schema, since the XPointer
framework <a href="#xptrframework">[XPTR]</a> is defined for all XML media
types. Other media types must explicitly specify a compatible fragment
identifier syntax.


</p></div><p>The schema component reference core defines reference to a schema component
in the context of an assembled XML Schema. <a href="#section-path"><b>4 Schema Component Paths</b></a>
defines this
relationship between an assemblage of schema components and component paths.
Schema assembly is described in
<a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#composition">Section
4 of XML Schema Part 1: Structures</a>.
</p><p>For the purposes of component paths, a
missing component
(see <a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#conformance-missing">
Section 5.3 of XML Schema Part 1: Structures</a>)
cannot be used to
construct a valid path; nor can a schema component be successfully referenced
through a path that references a missing component.
</p><p>[<a title="absolute schema component designator" id="key-scd" name="key-scd">Definition</a>: An
<b>absolute schema component designator</b> identifies
a particular schema component; it
consists of two parts: a designator
for the assembled schema (a <a title="schema designator" href="#key-sd">schema designator</a>), and a designator for a
particular schema component or schema components relative (a <a title="relative schema component designator" href="#key-relative-scd">relative
schema component designator</a>) to that assembled schema.]
</p><p>Syntactically, the first part is a URI without a fragment
identifier, and the second part
is an XPointer fragment identifier. An absolute schema component designator
therefore is a URI reference.
For example:
http://example.org/schemas/po.xsd#xscd(/type::purchaseOrderType)
</p><p>
Note that a schema component designator may contain Unicode characters
that are not allowed in URIs. Any such characters must be encoded and escaped
to obtain a URI suitable for retrieval, if retrieval is required.
</p><p>[<a title="relative schema component designator" id="key-relative-scd" name="key-relative-scd">Definition</a>: A
    <b>relative schema component designator</b>
    identifies a particular schema component relative to
    some current assembled schema; it
    is expressed as an <a href="http://www.w3.org/TR/xptr-framework/#scheme">XPointer scheme</a>
    <code> xscd()</code> that uses a <a title="schema component path" href="#key-scp">schema component path</a>
    as the <a href="http://www.w3.org/TR/xptr-framework/#NT-SchemeData">scheme data</a>.]  This
    XPointer scheme may be used in combination with the
    <a href="http://www.w3.org/TR/xptr-xmlns/#NT-XmlnsSchemeData"><span>XPointer
    <code>xmlns()</code> scheme</span></a>
    <a href="#xptrxmlns">[XPTR XMLNS]</a>.
    It is not
    designed to be used in
    combination with other XPointer schemes.
 The construction and syntax of schema component paths are described in
    <a href="#section-path"><b>4 Schema Component Paths</b></a>.
 </p><div class="div2">
<h3><a id="section-scd-syntax" name="section-scd-syntax" />3.1 Schema Component Designator Syntax</h3>
<h5><a id="N1034B" name="N1034B" />EBNF</h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-SchemaComponentDesignator" name="NT-SchemaComponentDesignator" />[1]   </td><td><code>SchemaComponentDesignator</code></td><td>   ::=   </td><td><code><a href="#NT-AbsoluteSchemaComponentDesignator">AbsoluteSchemaComponentDesignator</a> |
        <a href="#NT-RelativeSchemaComponentDesignator">
            RelativeSchemaComponentDesignator</a></code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AbsoluteSchemaComponentDesignator" name="NT-AbsoluteSchemaComponentDesignator" />[2]   </td><td><code>AbsoluteSchemaComponentDesignator</code></td><td>   ::=   </td><td><code><a href="#NT-SchemaDesignator">SchemaDesignator</a> '#'
        <a href="#NT-RelativeSchemaComponentDesignator">
            RelativeSchemaComponentDesignator</a></code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-SchemaDesignator" name="NT-SchemaDesignator" />[3]   </td><td><code>SchemaDesignator</code></td><td>   ::=   </td><td><code><a href="#NT-AnyURI">AnyURI</a></code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AnyURI" name="NT-AnyURI" />[4]   </td><td><code>AnyURI</code></td><td>   ::=   </td><td><code><a href="http://www.w3.org/TR/xml/#NT-Char">Char</a>*</code></td><td><i>/* IRI reference: no fragment identifier */</i></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-RelativeSchemaComponentDesignator" name="NT-RelativeSchemaComponentDesignator" />[5]   </td><td><code>RelativeSchemaComponentDesignator</code></td><td>   ::=   </td><td><code><a href="#NT-XmlnsPointerPart">XmlnsPointerPart</a>*
        <a href="#NT-XscdPointerPart">XscdPointerPart</a>
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-XmlnsPointerPart" name="NT-XmlnsPointerPart" />[6]   </td><td><code>XmlnsPointerPart</code></td><td>   ::=   </td><td><code>
    'xmlns' '(' <a href="http://www.w3.org/TR/xptr-xmlns/#NT-XmlnsSchemeData">XmlnsSchemeData</a> ')'
    </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-XscdPointerPart" name="NT-XscdPointerPart" />[7]   </td><td><code>XscdPointerPart</code></td><td>   ::=   </td><td><code>'xscd' '(' <a href="#NT-SchemaComponentPath">SchemaComponentPath</a> ')'
   </code></td></tr></tbody></table></div><div class="div2">
<h3><a id="section-canonical" name="section-canonical" />3.2 Canonical Schema Component Designators</h3><p>[<a title="canonical schema component designator" id="key-canonical-scd" name="key-canonical-scd">Definition</a>:
A <b>canonical schema component designator</b>
is an absolute schema component designator that is a URI
that has been mapped from a LEIRI to an IRI in accordance
with the rules given in <a href="#leiri">[LEIRI]</a>, mapped from an IRI to a URI in
accordance with
the rules given in RFC 3987<a href="#rfc3987">[RFC 3987]</a>, and
normalized according to the rules of
syntax-based normalization given there;
and where the relative schema component designator consists of an
<code>xmlns</code> XPointer pointer part (if required) followed
by a <a title="canonicalized xscd XPointer pointer part" href="#key-canonicalized-xscd"><span>canonicalized <code>xscd</code> XPointer pointer part</span></a>.
]</p><p>
[<a title="canonicalized xscd XPointer pointer part" id="key-canonicalized-xscd" name="key-canonicalized-xscd">Definition</a>:
A <b><span>canonicalized <code>xscd</code> XPointer pointer part</span></b> is
  an <code>xscd</code> XPointer pointer part whose
  pointer data is a canonical schema
component path.
]
</p></div><div class="div2">
<h3><a id="section-equality" name="section-equality" />3.3 Equality of Schema Component Designators</h3><p>Many use cases for schema component designators call for them to be compared
for equality. A simple string comparison

may fail to correctly recognize equivalent
designators
with this scheme
because namespace prefixes may vary. However, comparison is still
straightforward.
</p><p>[<a title="schema component designators are equal" id="key-equal-scd" name="key-equal-scd">Definition</a>: Two
<b>schema component designators are equal</b> if they are absolute
and their URIs are equal or if they are relative to the
same schema, and their <a title="schema component paths are equal" href="#key-equal-path">schema component paths are
equal</a>.]
</p></div></div><div class="div1">
<h2><a id="section-path" name="section-path" />4 Schema Component Paths</h2><p>An assembled schema forms a rooted graph of
schema components and property records, where
certain schema component and property record
properties contain other schema components and property
records as their
values (or part of their values). The graph arcs are
directed and
labelled. The graph may have cycles in it.
Schema component paths can be regarded as being
constructed step-by-step by traversing the schema component properties,
starting at the schema description schema component. Within this graph there may
be more than one path to a particular schema component.
This section describes

how paths are interpreted, and then
defines which paths are the canonical
ones.
</p><p>For the purposes of schema component paths, presume the
existence of an {identity constraint definitions} property of
the schema description component whose value is the union of all identity
constraint components in the assembled schema.

The XML Schema 1.1 specification defines
this property.
</p><div class="div2">
<h3><a id="section-path-traversal" name="section-path-traversal" />4.1 Schema Component Graph Traversal</h3><p>An assembled schema consists of a graph of schema components.
Schema property records and helper components are included
in the graph, but a schema component path never refers to them.  Traversal
in the graph passes <em>through</em> property records.


A schema component property that has other schema
components as its value
or as part of its value creates links in the graph which may be traversed
through one of the defined axes to construct a schema component path.

</p><p>[<a title="arc" id="key-arc" name="key-arc">Definition</a>: A traversal from one component to another
takes place across some particular component property. This property is
the <b>arc</b> of traversal.
]</p><p>[<a title="default arc" id="key-default-arc" name="key-default-arc">Definition</a>: A <b>default
arc</b> is a privileged
arc of traversal.
]
The default arcs are:
</p><blockquote><p>{type definition}<br />{content type}<br />{particle}<br />{simple type definition}<br />{attribute declaration}<br />{attribute uses}<br />{model group}<br />{particles}<br />{term}<br />{element declarations}<br />{facets}</p></blockquote><p><a href="#properties"><b>A Schema Component Properties (Non-Normative)</b></a> includes a summary of which
arcs act
as defaults and when.</p></div><div class="div2">
<h3><a id="section-path-syntax" name="section-path-syntax" />4.2 Schema Component Path Syntax</h3><div class="div3">
<h4><a id="section-scd-namespaces" name="section-scd-namespaces" />4.2.1 Namespaces</h4><p>The schema component axes defined in this document are considered to be
   names in no namespace.  They are always unprefixed and their names are
   considered reserved.  That is: no extension axis is permitted to have the
   same expanded name as any of the component axes specifically enumerated in
   <a href="#NT-Axis">Axis</a> production.</p><p>The schema component kinds defined in this document are contained in the
   namespace with the URI <code>http://www.w3.org/2009/xmlschema-ref</code>,
   which for the purposes of this specification is taken to be bound to the
   prefix <code>xscd</code>.
   </p></div><div class="div3">
<h4><a id="section-path-ebnf" name="section-path-ebnf" />4.2.2 EBNF for Schema Component Path Syntax</h4>
<h5><a id="N10443" name="N10443" />Path EBNF</h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-SchemaComponentPath" name="NT-SchemaComponentPath" />[8]   </td><td><code>SchemaComponentPath</code></td><td>   ::=   </td><td><code>( <a href="#NT-SchemaStep">SchemaStep</a> |
          <a href="#NT-StepSeparator">StepSepator</a>
          <a href="#NT-RelativeSchemaComponentPath">RelativeSchemaComponentPath</a> ) ('/' <a href="#NT-ExtensionAccessor">ExtensionAccessor</a>)?
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-SchemaStep" name="NT-SchemaStep" />[9]   </td><td><code>SchemaStep</code></td><td>   ::=   </td><td><code>'/'</code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-RelativeSchemaComponentPath" name="NT-RelativeSchemaComponentPath" />[10]   </td><td><code>RelativeSchemaComponentPath</code></td><td>   ::=   </td><td><code><a href="#NT-Step">Step</a> |
        <a href="#NT-Step">Step</a>
        <a href="#NT-StepSeparator">StepSeparator</a>
        <a href="#NT-RelativeSchemaComponentPath">RelativeSchemaComponentPath</a>
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-StepSeparator" name="NT-StepSeparator" />[11]   </td><td><code>StepSeparator</code></td><td>   ::=   </td><td><code>'/' |
        <a href="#NT-ComponentAxisSeparator">ComponentAxisSeparator</a>
    </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-ComponentAxisSeparator" name="NT-ComponentAxisSeparator" />[12]   </td><td><code>ComponentAxisSeparator</code></td><td>   ::=   </td><td><code>'//'</code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-Step" name="NT-Step" />[13]   </td><td><code>Step</code></td><td>   ::=   </td><td><code><a href="#NT-Axis">Axis</a>
        <a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>? |
        <a href="#NT-AbbrevStep">AbbrevStep</a>
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AbbrevStep" name="NT-AbbrevStep" />[14]   </td><td><code>AbbrevStep</code></td><td>   ::=   </td><td><code><a href="#NT-AbbrevAttributeStep">AbbrevAttributeStep</a> |
        <a href="#NT-AbbrevElementStep">AbbrevElementStep</a> |
        <a href="#NT-AbbrevTypeStep">AbbrevTypeStep</a> |
        <a href="#NT-AbbrevCurrentComponentStep">AbbrevCurrentComponentStep</a> |
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AbbrevAttributeStep" name="NT-AbbrevAttributeStep" />[15]   </td><td><code>AbbrevAttributeStep</code></td><td>   ::=   </td><td><code>'@' <a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>?
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AbbrevElementStep" name="NT-AbbrevElementStep" />[16]   </td><td><code>AbbrevElementStep</code></td><td>   ::=   </td><td><code><a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>?
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AbbrevTypeStep" name="NT-AbbrevTypeStep" />[17]   </td><td><code>AbbrevTypeStep</code></td><td>   ::=   </td><td><code>'~' <a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>?
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-AbbrevCurrentComponentStep" name="NT-AbbrevCurrentComponentStep" />[18]   </td><td><code>AbbrevCurrentComponentStep</code></td><td>   ::=   </td><td><code>'.' <a href="#NT-Predicate">Predicate</a>?</code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-Axis" name="NT-Axis" />[19]   </td><td><code>Axis</code></td><td>   ::=   </td><td><code>
      'schemaAttribute' '::' | 'schemaElement' '::' |
      'type' '::' |
      'attributeGroup' '::' | 'group' '::' |
      'identityConstraint' '::' |
      'assertion' '::' | 'alternative' '::' |
      'notation' '::' |
      'model' '::' |
      'anyAttribute' '::' | 'any' '::' |
      'facet' '::' |
      'scope' '::' | 'context' '::' |
      'substitutionGroup' '::' |
      'baseType' '::' | 'itemType' '::' | 'memberType' '::' | 'primitiveType' '::' |
      'key' '::' |
      'annotation' '::' |
      'component' '::' | 'currentComponent' '::' |
      'attributeUse' '::' | 'particle' '::' |
      <a href="#NT-ExtensionAxis">ExtensionAxis</a>
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-NameTest" name="NT-NameTest" />[20]   </td><td><code>NameTest</code></td><td>   ::=   </td><td><code><a href="http://www.w3.org/TR/REC-xml-names/#NT-QName">QName</a> |
   <a href="#NT-WildcardNameTest">WildcardNameTest</a> | '0'
   </code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-WildcardNameTest" name="NT-WildcardNameTest" />[21]   </td><td><code>WildcardNameTest</code></td><td>   ::=   </td><td><code>'*'</code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-ExtensionAccessor" name="NT-ExtensionAccessor" />[22]   </td><td><code>ExtensionAccessor</code></td><td>   ::=   </td><td><code><a href="http://www.w3.org/TR/REC-xml-names/#NT-QName">QName</a> '(' ')'</code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-ExtensionAxis" name="NT-ExtensionAxis" />[23]   </td><td><code>ExtensionAxis</code></td><td>   ::=   </td><td><code><a href="http://www.w3.org/TR/REC-xml-names/#NT-QName">QName</a> '::'</code></td></tr></tbody><tbody><tr valign="baseline"><td><a id="NT-Predicate" name="NT-Predicate" />[24]   </td><td><code>Predicate</code></td><td>   ::=   </td><td><code>'[' [0]*[1-9][0-9]* ']'</code></td></tr></tbody></table><div class="note"><p class="prefix"><b>Note:</b></p><p>The EBNF above defines a syntax for invoking an accessor after the
last step of the path and for using extension axes.  This syntax is included for
extensibility. A specification that wishes to make use of these extensions must
define the detailed syntax and semantics
(see <a href="#section-conformance"><b>5 Conformance</b></a>).
</p></div></div><div class="div3">
<h4><a id="section-path-examples" name="section-path-examples" />4.2.3 Examples of Schema Component Paths (Non-Normative)</h4><p>The following examples assume the namespace prefixes have been properly
bound.</p><p>A schema component path referring to the type (either simple or complex)
whose local name is <code>title</code> and which is in the namespace denoted by
the prefix <code>my</code>:</p><div class="exampleInner"><pre>/type::my:title</pre></div><p>A schema component path referring to the globally declared element whose
local name is <code>title</code> and which is in the namespace denoted by the
prefix <code>my</code>:</p><div class="exampleInner"><pre>/schemaElement::my:title</pre></div><p>A schema component path referring to the globally declared attribute whose
local name is <code>title</code> and which is in the namespace denoted by the
prefix <code>my</code>:</p><div class="exampleInner"><pre>/schemaAttribute::my:title</pre></div><p>A schema component path referring to the globally declared attribute group
whose local name is <code>title</code> and which is in the namespace denoted by
the prefix <code>my</code>:</p><div class="exampleInner"><pre>/attributeGroup::my:title</pre></div><p>A schema component path referring to the pattern facet of the globally
declared simple type whose local name is <code>title</code> which is in the
namespace denoted by <code>my</code>:
</p><div class="exampleInner"><pre>/type::my:title/facet::pattern</pre></div><p>Given this schema fragment for a schema whose target namespace is denoted by
the prefix <code>my</code>:</p><div class="exampleInner"><pre>
&lt;xs:complexType name="articleType"&gt;
   &lt;xs:sequence&gt;
      &lt;xs:element ref="my:section"/&gt;
      &lt;xs:element name="appendix" type="my:sectionType"/&gt;
   &lt;/xs:sequence&gt;
&lt;/xs:complexType&gt;

&lt;xs:element name="chapter"&gt;
   &lt;xs:complexType&gt;
      &lt;xs:sequence&gt;
         &lt;xs:element ref="my:title" minOccurs="0" maxOccurs="unbounded"/&gt;
         &lt;xs:any namespace="##other" minOccurs="0" maxOccurs="unbounded"/&gt;
      &lt;/xs:sequence&gt;
      &lt;xs:attribute name="name" type="xs:string"/&gt;
      &lt;xs:anyAttribute namespace="##other" use="optional"/&gt;
   &lt;/xs:complexType&gt;
&lt;/xs:element&gt;
</pre></div><p>The following schema component path refers to the first element of the named
complex type:</p><div class="exampleInner"><pre>/type::my:articleType/model::sequence/schemaElement::my:section</pre></div><p>And the following schema component path refers to the second:</p><div class="exampleInner"><pre>/type::my:articleType/model::sequence/schemaElement::my:appendix</pre></div><p>A schema component path referring to the (anonymous) complex type of the
globally defined element:</p><div class="exampleInner"><pre>/schemaElement::my:chapter/type::0</pre></div><p>A schema component path that refers to the wildcard in the globally defined
element:</p><div class="exampleInner"><pre>/schemaElement::my:chapter/type::0/model::sequence/any::*</pre></div><p>A schema component path that refers to the attribute of the globally defined
element:</p><div class="exampleInner"><pre>/schemaElement::my:chapter/type::0/schemaAttribute::name</pre></div></div></div><div class="div2">
<h3><a id="section-path-interpret" name="section-path-interpret" />4.3 Interpretation of Schema Component Paths</h3><p>[<a title="schema component path" id="key-scp" name="key-scp">Definition</a>: A
<b>schema component path</b> selects a sequence of
schema components in the context of an assembled schema; it is a series
of <a title="step" href="#key-scp-step">steps</a> separated by
'<code>/</code>' or '<code>//</code>'.  Complete schema component paths always
start with either '<code>/</code>' or '<code>//</code>'.
]
</p><p>
[<a title="step" id="key-scp-step" name="key-scp-step">Definition</a>: A <b>step</b>
consists of a <a title="axis" href="#key-scp-axis">schema component
axis</a> and a <a title="schema component name test" href="#key-scp-nametest">schema component name
test</a> and
an optional <a title="schema component positional predicate" href="#key-scp-pospred">positional predicate</a>.
It selects a sequence of schema components that are linked to a
source component through an arc that matches the axis, pass the name test,
and are selected by the positional predicate, if any.
]
Schema component axes are described in <a href="#section-axis"><b>4.4 Schema Component Path Axes</b></a>.
</p><p>In general the syntax of a step of the schema component path has the
following form:
</p><p>The predicate is optional and there are abbreviated forms for some steps.</p><p>[<a title="schema component name test" id="key-scp-nametest" name="key-scp-nametest">Definition</a>: A
<b>schema component name
test</b> is a condition on name of the components selected by the schema
component path step.] A schema component name test
either gives a localname, possibly with a namespace prefix, or consists of a
just the wildcard character ('<code>*</code>'), or just the character zero
('<code>0</code>').
</p><p>A schema component name test of this form is true if the QName formed from
the namespace name and local name specified in the the schema component name
test is equal to the value of the component-name() accessor of the schema
component. For more information on namespace binding for QName interpretation
see <a href="#section-namespaces"><b>4.3.2 Namespaces</b></a>.</p><p>A schema component name test of this form is true
for anonymous type definitions.  An anonymous type definition's
component-name() accessor returns "0".
This name cannot have any conflict with any possible named component, as 0 is
not a valid name start character.
</p><p>A schema component name test of this form is true for all linked components
matching the given axis.</p><p>[<a title="schema component positional predicate" id="key-scp-pospred" name="key-scp-pospred">Definition</a>:
A <b>schema component positional predicate</b> is a condition on the
relative position of the component in the sequence of matching components from
the schema component path step.] A schema component position predicate
is true if the position of the target component in the sequence of
components selected by the axis and name test is equal
to the positive integer given in the predicate.   <span>Counting
starts at 1.</span>
</p><p>
A path consisting of just '<code>/</code>' selects the schema description
component.
</p><p>
A path of the form <code>/<var>S1</var></code> selects
components linked to the schema description component in accordance with the
step <code><var>S1</var></code>.
</p><p>
A path of the form <code><var>S1</var>/<var>S2</var></code> is interpreted
by gathering the sequence of source components and then selecting any
schema component that is linked to one of the source components in accordance
with the step <code><var>S2</var></code>.  The sequence of source components
consists of the sequence of components selected by <code><var>S1</var></code>
followed by the components selected by the elided-component
axis on those components.
</p><p>
A path of the form <code><var>S1</var>//<var>S2</var></code> is also
interpreted by gathering the sequence of source components and then selecting
any schema component that is linked to one of the source components in
accordance with the step <code><var>S2</var></code>.  In this case the
sequence of source components consists of the sequence of components selected
by <code><var>S1</var></code> followed by the application of
the component axis on members of that sequence.
</p><p>A path of the form <code><var>S1</var></code> selects all schema components
linked to the initial source component in accordance with the step
<code><var>S1</var></code>.
</p><p>Implementations will have to exercise care to
properly handle circularities in the component graph in determining the set of
components matched by a path.
</p><div class="div3">
<h4><a id="section-incomplete-paths" name="section-incomplete-paths" />4.3.1 Incomplete Schema Component Paths</h4><p>Incomplete schema component paths may be constructed starting at
some specific source component following the construction rules given here.
Such paths will not start with a leading slash. Correct interpretation of
such incomplete (relative) paths depends on the initial source component.
External specifications sanctioning relative schema component paths must
therefore define the initial source component to use to interpret the schema
component path.  In this specification, "schema component path"
always refers to a complete schema component path starting at the root
schema description component, unless explicitly stated otherwise.
</p><p>To emphasize the incompleteness of such paths, the current component step
syntax may be used (<code>.</code>) for the head step. For example, if
the initial source component is a complex type, the following paths are
equivalent and
designate the element declaration with the QName <code>my:section</code>
within the sequence model group of that type:
</p><div class="exampleInner"><pre>model::sequence/schemaElement::my:section</pre></div><div class="exampleInner"><pre>./model::sequence/schemaElement::my:section</pre></div></div><div class="div3">
<h4><a id="section-namespaces" name="section-namespaces" />4.3.2 Namespaces</h4><p>Schema component paths use QNames to refer to schema components.
Interpretation of these QNames therefore depends on namespace bindings.
When schema component paths are used in the context of schema component
designators (<a href="#section-scds"><b>3 Schema Component Designators</b></a>), the <code>xmlns()</code> XPointer
scheme defines those namespace bindings.  In the context of an XML document the
namespace prefixes will be bound in the conventional way (using the [in-scope namespaces] property of the element information item). Other host languages and
some XML applications will define their own namespace binding rules.
While the <code>xmlns()</code> scheme does not provide for defining a
default namespace, other mechanisms may do so.  In such contexts, schema
component paths allow and apply the default namespace.
</p><p>Note also that the <code>form</code> (and <code>elementFormDefault</code>
and <code>attributeFormDefault</code>) values apply as well. Since, for example,
a local attribute declaration component with the form <code>unqualified</code>
will have an empty <code>{target namespace}</code>, the QName for that
declaration will have no prefix.
</p><p>For example, consider the path:</p><div class="exampleInner"><pre>//quantity</pre></div><p>This path
designates global or local element declarations whose local
name is <code>quantity</code> and which are either in no
namespace, are local elements whose form is <code>unqualified</code>,
or are in the default namespace (assuming there is a such a namespace
binding).</p><p>For types, form is not relevant.</p><div class="exampleInner"><pre>/~Items//quantity</pre></div><p>This path designates global or local element declarations whose local name
is <code>quantity</code>, where these declarations
are in the subgraph represented by the global complex type component whose
local name is <code>Items</code>.  As in the previous
example, the element declaration may either be in schema with no target
namespace, in the default namespace, or a local element declaration with the
form <code>unqualified</code>. The complex type <code>Items</code> must be in
the default namespace or in a schema with no target namespace.
</p><p>This path designates global or local attribute
declarations whose local name is <code>partNum</code> where these declarations
are in the subgraph represented by the global complex type component whose
local name is <code>Items</code>.  Again, the complex type is either in the
default namespace or in a schema with no target namespace, and the attribute
declaration must be global attributes in a schema with no target namespace, in
the default namespace, or be local declarations with the form
<code>unqualified</code>.
</p><div class="exampleInner"><pre>/~Items//@partNum</pre></div></div></div><div class="div2">
<h3><a id="section-axis" name="section-axis" />4.4 Schema Component Path Axes</h3><p>
[<a title="axis" id="key-scp-axis" name="key-scp-axis">Definition</a>: A schema component path <b>axis</b>
contains specific components linked to the
current context component through certain kinds of arcs.
Unless otherwise indicated, an axis applied to
a component that has no arc of the required kind designates no components.
]
</p><div class="div3">
<h4><a id="section-axis-currentComponent" name="section-axis-currentComponent" />4.4.1 The currentComponent Axis</h4><p>[<a title="currentComponent axis" id="axis-currentComponent" name="axis-currentComponent">Definition</a>: The
<b><span><code>currentComponent</code></span></b> axis contains the current component.
]
</p>
<h5><a id="N106EB" name="N106EB" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-CurrentComponentAxis" name="NT-CurrentComponentAxis" />[25]   </td><td><code>CurrentComponentAxis</code></td><td>   ::=   </td><td><code>'currentComponent' '::</code></td></tr></tbody><tbody><tr valign="baseline"><td>[18]   </td><td><a href="#NT-AbbrevCurrentComponentStep"><code>AbbrevCurrentComponentStep</code></a></td><td>   ::=   </td><td><code>'.' <a href="#NT-Predicate">Predicate</a>?</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-annotation" name="section-axis-annotation" />4.4.2 The annotation Axis</h4><p>[<a title="annotation axis" id="axis-annotation" name="axis-annotation">Definition</a>: The
<b><span><code>annotation</code></span></b> axis contains annotation
components linked to the current component through {annotation} or
{annotations} arcs, which are the components returned
by the annotations() accessor.
]
</p>
<h5><a id="N10706" name="N10706" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AnnotationAxis" name="NT-AnnotationAxis" />[26]   </td><td><code>AnnotationAxis</code></td><td>   ::=   </td><td><code>'annotation' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-schemaAttribute" name="section-axis-schemaAttribute" />4.4.3 The schemaAttribute Axis</h4><p>[<a title="schemaAttribute axis" id="axis-schemaAttribute" name="axis-schemaAttribute">Definition</a>: The
<b><span><code>schemaAttribute</code></span></b> axis contains attribute
declaration components linked to the current component through
{attribute declaration} or {attribute declarations} arcs,
which are those components returned by the component-linked() accessor whose
component-kind() is equal to <code><span>xscd:</span>attribute-declaration</code>.
]
</p>
<h5><a id="N10725" name="N10725" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-SchemaAttributeAxis" name="NT-SchemaAttributeAxis" />[27]   </td><td><code>SchemaAttributeAxis</code></td><td>   ::=   </td><td><code>'schemaAttribute' '::'</code></td></tr></tbody><tbody><tr valign="baseline"><td>[15]   </td><td><a href="#NT-AbbrevAttributeStep"><code>AbbrevAttributeStep</code></a></td><td>   ::=   </td><td><code>'@' <a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>?
   </code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-schemaElement" name="section-axis-schemaElement" />4.4.4 The schemaElement Axis</h4><p>[<a title="schemaElement axis" id="axis-schemaElement" name="axis-schemaElement">Definition</a>: The
<b><span><code>schemaElement</code></span></b> axis contains element
declaration components linked to the current component through
{element declarations}, {term}, {particle},
{particles}, or {content type}, which are the components returned by the
term() accessor whose component-kind() is equal to
<code><span>xscd:</span>element-declaration</code>, together with {element declarations}.
]
</p>
<h5><a id="N10746" name="N10746" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-SchemaElementAxis" name="NT-SchemaElementAxis" />[28]   </td><td><code>SchemaElementAxis</code></td><td>   ::=   </td><td><code>'schemaElement' '::'</code></td></tr></tbody><tbody><tr valign="baseline"><td>[16]   </td><td><a href="#NT-AbbrevElementStep"><code>AbbrevElementStep</code></a></td><td>   ::=   </td><td><code><a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>?
   </code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-type" name="section-axis-type" />4.4.5 The type Axis</h4><p>[<a title="type axis" id="axis-type" name="axis-type">Definition</a>: The <b><span><code>type</code></span></b>
axis contains simple type definition
and complex type definition components linked to the current component through
{type definition}, {type definitions}, {content type},
or {simple type definition} arcs, which are the components
returned by the component-children() accessor whose
component-kind() is equal to either
<code><span>xscd:</span>complex-type-definition</code> or
<code><span>xscd:</span>simple-type-definition</code>.]
</p>
<h5><a id="N1076D" name="N1076D" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-TypeAxis" name="NT-TypeAxis" />[29]   </td><td><code>TypeAxis</code></td><td>   ::=   </td><td><code>'type' '::'</code></td></tr></tbody><tbody><tr valign="baseline"><td>[17]   </td><td><a href="#NT-AbbrevTypeStep"><code>AbbrevTypeStep</code></a></td><td>   ::=   </td><td><code>'~' <a href="#NT-NameTest">NameTest</a>
        <a href="#NT-Predicate">Predicate</a>?
   </code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-agroup" name="section-axis-agroup" />4.4.6 The attributeGroup Axis</h4><p>[<a title="attributeGroup axis" id="axis-attributeGroup" name="axis-attributeGroup">Definition</a>: The
<b><span><code>attributeGroup</code></span></b> axis contains
attribute group definition components linked to the current component through
{attribute group definitions} arcs, which are those components
returned by the component-linked() accessor whose component-kind() is equal to
<code><span>xscd:</span>attribute-group-definition</code>.]
</p>
<h5><a id="N1078E" name="N1078E" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AttributeGroupAxis" name="NT-AttributeGroupAxis" />[30]   </td><td><code>AttributeGroupAxis</code></td><td>   ::=   </td><td><code>'attributeGroup' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-groupdef" name="section-axis-groupdef" />4.4.7 The group Axis</h4><p>[<a title="group axis" id="axis-group" name="axis-group">Definition</a>: The
<b><span><code>group</code></span></b> axis contains
model group definition components linked to the current component through
{model group definitions} arcs, which are those components returned
by the component-linked() accessor whose component-kind() is equal to
<code><span>xscd:</span>model-group-definition</code>.
]
</p>
<h5><a id="N107AD" name="N107AD" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-GroupAxis" name="NT-GroupAxis" />[31]   </td><td><code>GroupAxis</code></td><td>   ::=   </td><td><code>'group' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-idc" name="section-axis-idc" />4.4.8 The identityConstraint Axis</h4><p>[<a title="identityConstraint axis" id="axis-identityConstraint" name="axis-identityConstraint">Definition</a>: The
<b><span><code>identityConstraint</code></span></b> axis contains
identity constraint definition components linked to the current component
through {identity constraint definitions} arcs, which are those
components returned by the component-linked() accessor whose component-kind()
is equal to <code><span>xscd:</span>identity-constraint-definition</code>.
]
</p>
<h5><a id="N107CC" name="N107CC" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-IdentityConstraintAxis" name="NT-IdentityConstraintAxis" />[32]   </td><td><code>IdentityConstraintAxis</code></td><td>   ::=   </td><td><code>'identityConstraint' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-assertion" name="section-axis-assertion" />4.4.9 The assertion Axis</h4><p>[<a title="assertion axis" id="axis-assertion" name="axis-assertion">Definition</a>: The
<b><span><code>assertion</code></span></b> axis contains
assertion components linked to the current component
through {assertions}, {value}, or {facets} arcs, which are those components
returned by the assertions() accessor.]
</p>
<h5><a id="N107E5" name="N107E5" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AssertionAxis" name="NT-AssertionAxis" />[33]   </td><td><code>AssertionAxis</code></td><td>   ::=   </td><td><code>'assertion' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-alternative" name="section-axis-alternative" />4.4.10 The alternative Axis</h4><p>[<a title="alternative-axis" id="axis-alternatives" name="axis-alternatives">Definition</a>: The
<b><span><code>alternative</code></span></b> axis
contains
type alternative components linked to the current component
through {alternatives}, {default type definition}, or {type table} arcs,
which are those components
returned by the component-linked() accessor whose component-kind() is
equal to <code><span>xscd:</span>type-alternative</code>.
]
</p><div class="note"><p class="prefix"><b>Note:</b></p><p>The {default type definition} of the type alternatives table of an
element declaration is actually a type alternative component and will be
selected by the alternative axis. </p></div>
<h5><a id="N10807" name="N10807" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AlternativeAxis" name="NT-AlternativeAxis" />[34]   </td><td><code>AlternativeAxis</code></td><td>   ::=   </td><td><code>'alternative' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-notation" name="section-axis-notation" />4.4.11 The notation Axis</h4><p>[<a title="notation axis" id="axis-notation" name="axis-notation">Definition</a>: The
<b><span><code>notation</code></span></b> axis contains
notation declaration components linked to the current component
through {notation declarations}
arcs, which are the components returned by the component-linked() accessor
whose component-kind() is equal to <code><span>xscd:</span>notation-declaration</code>.]
</p>
<h5><a id="N10826" name="N10826" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-NotationAxis" name="NT-NotationAxis" />[35]   </td><td><code>NotationAxis</code></td><td>   ::=   </td><td><code>'notation' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-model" name="section-axis-model" />4.4.12 The model Axis</h4><p>[<a title="model axis" id="axis-model" name="axis-model">Definition</a>: The
<b><span><code>model</code></span></b> axis contains
model group components linked to the current component
through {model group}, {term}, {particle}, {particles}, or {content type}
arcs, which are the components returned by the term() accessor
whose component-kind() is equal to <code><span>xscd:</span>model-group</code>.
]
</p>
<h5><a id="N10845" name="N10845" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-ModelAxis" name="NT-ModelAxis" />[36]   </td><td><code>ModelAxis</code></td><td>   ::=   </td><td><code>'model' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-anyAttribute" name="section-axis-anyAttribute" />4.4.13 The anyAttribute Axis</h4><p>[<a title="anyAttribute axis" id="axis-anyAttribute" name="axis-anyAttribute">Definition</a>: The
<b><span><code>anyAttribute</code></span></b> axis contains
wildcard components linked to the current component
through {attribute wildcard} arcs.]
</p>
<h5><a id="N1085E" name="N1085E" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AnyAttributeAxis" name="NT-AnyAttributeAxis" />[37]   </td><td><code>AnyAttributeAxis</code></td><td>   ::=   </td><td><code>'anyAttribute' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-any" name="section-axis-any" />4.4.14 The any Axis</h4><p>[<a title="any axis" id="axis-any" name="axis-any">Definition</a>: The <b><span><code>any</code></span></b>
axis contains
wildcard components linked to the current component
through {wildcard}, {term}, {particle}, {particles}, {content type}, or
{open content} arcs, which is the components returned by the
term() accessor whose component-kind() is equal to
<code><span>xscd:</span>wildcard</code>. ]
</p>
<h5><a id="N1087D" name="N1087D" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AnyAxis" name="NT-AnyAxis" />[38]   </td><td><code>AnyAxis</code></td><td>   ::=   </td><td><code>'any' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-facet" name="section-axis-facet" />4.4.15 The facet Axis</h4><p>[<a title="facet axis" id="axis-facet" name="axis-facet">Definition</a>: The
<b><span><code>facet</code></span></b> axis contains
facet components linked to the current component
through {facets} or {fundamental facets} arcs, which is the components returned
by component-linked() whose component-kind() is equal
to <code><span>xscd:</span>facet</code>.
]</p>
<h5><a id="N1089B" name="N1089B" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-FacetAxis" name="NT-FacetAxis" />[39]   </td><td><code>FacetAxis</code></td><td>   ::=   </td><td><code>'facet' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-scope" name="section-axis-scope" />4.4.16 The scope Axis</h4><p>[<a title="scope axis" id="axis-scope" name="axis-scope">Definition</a>: The
<b><span><code>scope</code></span></b> axis contains
complex type definition, attribute group definition, or
model group definition components linked to the current component
through {scope} and {parent} arcs, which are the components returned from
the component-scope() accessor.
]
</p>
<h5><a id="N108B4" name="N108B4" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-ScopeAxis" name="NT-ScopeAxis" />[40]   </td><td><code>ScopeAxis</code></td><td>   ::=   </td><td><code>'scope' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-context" name="section-axis-context" />4.4.17 The context Axis</h4><p>[<a title="context axis" id="axis-context" name="axis-context">Definition</a>: The
<b><span><code>context</code></span></b> axis contains
complex type definition, attribute declaration, or
element declaration components linked to the current component
through {context} arcs.
]
</p>
<h5><a id="N108CD" name="N108CD" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-ContextAxis" name="NT-ContextAxis" />[41]   </td><td><code>ContextAxis</code></td><td>   ::=   </td><td><code>'context' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-substitutionGroup" name="section-axis-substitutionGroup" />4.4.18 The substitutionGroup Axis</h4><p>[<a title="substitutionGroup axis" id="axis-substitutionGroup" name="axis-substitutionGroup">Definition</a>: The
<b><span><code>substitutionGroup</code></span></b> axis contains
element declaration components linked to the current component
through {substitution group affiliation} and {substitution group affiliations}
arcs.
]
</p>
<h5><a id="N108E6" name="N108E6" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-SubstitutionGroupAxis" name="NT-SubstitutionGroupAxis" />[42]   </td><td><code>SubstitutionGroupAxis</code></td><td>   ::=   </td><td><code>'substitutionGroup' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-baseType" name="section-axis-baseType" />4.4.19 The baseType Axis</h4><p>[<a title="baseType axis" id="axis-baseType" name="axis-baseType">Definition</a>: The
<b><span><code>baseType</code></span></b> axis contains
simple type definition and complex type definition components linked to the
current component through {base type definition} arcs.
]
</p>
<h5><a id="N108FF" name="N108FF" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-BaseTypeAxis" name="NT-BaseTypeAxis" />[43]   </td><td><code>BaseTypeAxis</code></td><td>   ::=   </td><td><code>'baseType' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-itemType" name="section-axis-itemType" />4.4.20 The itemType Axis</h4><p>[<a title="itemType axis" id="axis-itemType" name="axis-itemType">Definition</a>: The
<b><span><code>itemType</code></span></b> axis contains
simple type definition components linked to the
current component through {item type definition} arcs.
]
</p>
<h5><a id="N10918" name="N10918" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-ItemTypeAxis" name="NT-ItemTypeAxis" />[44]   </td><td><code>ItemTypeAxis</code></td><td>   ::=   </td><td><code>'itemType' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-memberType" name="section-axis-memberType" />4.4.21 The memberType Axis</h4><p>[<a title="memberType axis" id="axis-memberType" name="axis-memberType">Definition</a>: The
<b><span><code>memberType</code></span></b> axis contains
simple type definition components linked to the
current component through {member type definitions}
arcs. ]
</p>
<h5><a id="N10931" name="N10931" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-MemberTypeAxis" name="NT-MemberTypeAxis" />[45]   </td><td><code>MemberTypeAxis</code></td><td>   ::=   </td><td><code>'memberType' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-primitiveType" name="section-axis-primitiveType" />4.4.22 The primitiveType Axis</h4><p>[<a title="primitiveType axis" id="axis-primitiveType" name="axis-primitiveType">Definition</a>: The
<b><span><code>primitiveType</code></span></b> axis contains
simple type definition components linked to the
current component through {primitive type definition}
arcs.]</p>
<h5><a id="N10949" name="N10949" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-PrimitiveTypeAxis" name="NT-PrimitiveTypeAxis" />[46]   </td><td><code>PrimitiveTypeAxis</code></td><td>   ::=   </td><td><code>'primitiveType' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-referencedKey" name="section-axis-referencedKey" />4.4.23 The key Axis</h4><p>[<a title="key axis" id="axis-key" name="axis-key">Definition</a>: The <b><span><code>key</code></span></b>
axis contains
identity constraint definition components linked to the
current component through {referenced key}
arcs.]
</p>
<h5><a id="N10962" name="N10962" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-KeyAxis" name="NT-KeyAxis" />[47]   </td><td><code>KeyAxis</code></td><td>   ::=   </td><td><code>'key' '::'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-attributeUse" name="section-axis-attributeUse" />4.4.24 The attributeUse Axis</h4><p>[<a title="attributeUse axis" id="axis-attributeUse" name="axis-attributeUse">Definition</a>: The
<b><span><code>attributeUse</code></span></b> axis contains attribute use components
linked to the current component through {attribute uses}.
]
</p>
<h5><a id="N1097B" name="N1097B" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-AttributeUseAxis" name="NT-AttributeUseAxis" />[48]   </td><td><code>AttributeUseAxis</code></td><td>   ::=   </td><td><code>'attributeUse' '::</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-particle" name="section-axis-particle" />4.4.25 The particle Axis</h4><p>[<a title="particle axis" id="axis-particle" name="axis-particle">Definition</a>: The
<b><span><code>particle</code></span></b> axis contains particle components
linked to the current component through {particles}.
]
</p>
<h5><a id="N10994" name="N10994" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-ParticleAxis" name="NT-ParticleAxis" />[49]   </td><td><code>ParticleAxis</code></td><td>   ::=   </td><td><code>'particle' '::</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-component" name="section-axis-component" />4.4.26 The component Axis</h4><p>[<a title="component axis" id="axis-component" name="axis-component">Definition</a>: The
<b><span><code>component</code></span></b> axis contains the transitive closure of
schema
components that are either linked to the schema description component or that
are linked to current component through default arcs.  That is, it contains
the transitive
closure of the component-children() accessor, as well as
component-linked()
accessor if the schema description is the current component.
]</p>
<h5><a id="N109AC" name="N109AC" /></h5><table summary="Scrap" class="scrap"><tbody><tr valign="baseline"><td><a id="NT-ComponentAxis" name="NT-ComponentAxis" />[50]   </td><td><code>ComponentAxis</code></td><td>   ::=   </td><td><code>'component' '::'</code></td></tr></tbody><tbody><tr valign="baseline"><td>[12]   </td><td><a href="#NT-ComponentAxisSeparator"><code>ComponentAxisSeparator</code></a></td><td>   ::=   </td><td><code>'//'</code></td></tr></tbody></table></div><div class="div3">
<h4><a id="section-axis-elided-component" name="section-axis-elided-component" />4.4.27 The elided-component Axis</h4><p>[<a title="elided-component axis" id="axis-elided-component" name="axis-elided-component">Definition</a>: The
<b><span><code>elided-component</code></span></b> axis contains complex type
definitions
linked to the current component through the {type definition} arc and the
transitive closure of all model group components linked to the current
component. That is, it contains the transitive closure of components returned
from the term() accessor whose component-kind() is equal to
<code><span>xscd:</span>model-group</code>, as well as components linked to the current component
through the {type definition} arc.
]
</p><p>There is no syntax for this axis: it is used to define the semantics of
certain paths.</p></div></div><div class="div2">
<h3><a id="section-accessors" name="section-accessors" />4.5 Accessors</h3><p>A set of accessors is defined on schema components.  For consistency, each
accessor is defined for every kind of schema component,
although several accessors return a constant empty value on some kinds of
schema components.</p><p>Where accessors return sequences, the order of components
accessed on one arc is as defined by the schema component model.  Components
accessed through default arcs precede components accessed through non-default
arcs.  Components are otherwise ordered as if arcs were accessed in the
following order:
</p><ul><li><p>{type definitions}</p></li><li><p>{type definition}</p></li><li><p>{base type definition}</p></li><li><p>{item type definition}</p></li><li><p>{member type definitions}</p></li><li><p>{primitive type definition}</p></li><li><p>{type table}</p></li><li><p>{alternatives}</p></li><li><p>{default type definition}</p></li><li><p>{simple type definition}</p></li><li><p>{element declarations}</p></li><li><p>{substitution group affiliations}</p></li><li><p>{substitution group affiliation}</p></li><li><p>{attribute declarations}</p></li><li><p>{attribute declaration}</p></li><li><p>{model group definitions}</p></li><li><p>{attribute group definitions}</p></li><li><p>{scope}</p></li><li><p>{parent}</p></li><li><p>{context}</p></li><li><p>{content type}</p></li><li><p>{particles}</p></li><li><p>{particle}</p></li><li><p>{term}</p></li><li><p>{model group}</p></li><li><p>{attribute uses}</p></li><li><p>{open content}</p></li><li><p>{wildcard}</p></li><li><p>{attribute wildcard}</p></li><li><p>{identity constraint definitions}</p></li><li><p>{referenced key}</p></li><li><p>{assertions}</p></li><li><p>{notation declarations}</p></li><li><p>{facets}</p></li><li><p>{fundamental facets}</p></li><li><p>{annotation}</p></li><li><p>{annotations}</p></li></ul><div class="div3">
<h4><a id="accessor-component-kind" name="accessor-component-kind" />4.5.1 component-kind Accessor</h4><p>The component-kind accessor returns <span>an <a href="http://www.w3.org/TR/2004/REC-xml-names11-20040204/#dt-expname">expanded name</a></span>
identifying the kind of the schema component. </p><table border="0" cellspacing="5" summary="component-kind accessor details"><thead><tr><th align="left">Component</th><th align="left">Result of component-kind()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top"><span>xscd:</span>attribute-declaration</td></tr><tr><td valign="top">Element Declaration</td><td valign="top"><span>xscd:</span>element-declaration</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top"><span>xscd:</span>complex-type-definition</td></tr><tr><td valign="top">Attribute Use</td><td valign="top"><span>xscd:</span>attribute-use</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top"><span>xscd:</span>attribute-group-definition</td></tr><tr><td valign="top">Model Group Definition</td><td valign="top"><span>xscd:</span>model-group-definition</td></tr><tr><td valign="top">Model Group</td><td valign="top"><span>xscd:</span>model-group</td></tr><tr><td valign="top">Particle</td><td valign="top"><span>xscd:</span>particle</td></tr><tr><td valign="top">Wildcard</td><td valign="top"><span>xscd:</span>wildcard</td></tr><tr><td valign="top">Identity‑Constraint Definition</td><td valign="top"><span>xscd:</span>identity-constraint-definition</td></tr><tr><td valign="top">Type Alternative</td><td valign="top"><span>xscd:</span>type-alternative</td></tr><tr><td valign="top">Assertion</td><td valign="top"><span>xscd:</span>assertion</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top"><span>xscd:</span>notation-declaration</td></tr><tr><td valign="top">Annotation</td><td valign="top"><span>xscd:</span>annotation</td></tr><tr><td valign="top">Schema</td><td valign="top"><span>xscd:</span>schema</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top"><span>xscd:</span>simple-type-definition</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top"><span>xscd:</span>facet</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top"><span>xscd:</span>facet</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-component-name" name="accessor-component-name" />4.5.2 component-name Accessor</h4><p>The component-name accessor returns zero or one xs:QName values giving the
name of the component.</p><table border="0" cellspacing="5" summary="component-name accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of component-name()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">the xs:QName formed
from the {name} and {target namespace} properties</td></tr><tr><td valign="top">Element Declaration</td><td valign="top">the xs:QName formed
from the {name} and {target namespace} properties</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">the xs:QName
formed from the {name} and {target namespace} properties; "0", if
{name} is absent</td></tr><tr><td valign="top">Attribute Use</td><td valign="top">empty</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">the xs:QName
formed from the {name} and {target namespace} properties</td></tr><tr><td valign="top">Model Group Definition</td><td valign="top">the xs:QName formed
from the {name} and {target namespace} properties</td></tr><tr><td valign="top">Model Group</td><td valign="top">the xs:QName formed from
an empty namespace name and the value of the component-variety() accessor as
the local name</td></tr><tr><td valign="top">Particle</td><td valign="top">empty</td></tr><tr><td valign="top">Wildcard</td><td valign="top">empty</td></tr><tr><td valign="top">Identity‑Constraint Definition</td><td valign="top">the xs:QName
formed from the {name} and {target namespace} properties</td></tr><tr><td valign="top">Assertion</td><td valign="top">empty</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">empty</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Annotation</td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">empty</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">the xs:QName formed
from the {name} and {target namespace} properties; "0", if {name} is
absent
</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">the xs:QName
formed with an empty namespace name and the value of the component-variety()
accessor as the local name</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">the xs:QName formed
with an empty namespace name and the value of the component-variety() accessor
as the local name</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-component-variety" name="accessor-component-variety" />4.5.3 component-variety Accessor</h4><p>The component-variety accessor returns zero or one strings identifying the
specific variety of that component kind.
</p><table border="0" cellspacing="5" summary="component-variety accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of component-variety()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">
"global"
if {scope} is "global" or if the value of the
{variety} property of {scope} is "global" (1.1);
"local" otherwise</td></tr><tr><td valign="top">Element Declaration </td><td valign="top">"global"
if {scope} is "global" or if the value of the {variety} property of {scope} is
"global" (1.1);
"local" otherwise</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">the value of
the {variety} property of the {content type} (1.1). Under the XML Schema 1.0
component model, there is no such property; instead returns "empty"
if the {content type} property has the value "empty",
"simple" if the {content type} property has a simple type declaration
as its value, "element-only" or "mixed" if the {content type} has a pair as a
value and that string is a member of the pair</td></tr><tr><td valign="top">Attribute Use </td><td valign="top">empty</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Model Group Definition </td><td valign="top">empty</td></tr><tr><td valign="top">Model Group </td><td valign="top">the value of the
{compositor} property, one of "sequence", "choice", and "all"</td></tr><tr><td valign="top">Particle</td><td valign="top">empty</td></tr><tr><td valign="top">Wildcard</td><td valign="top">the value of the
{process contents} property, one of "strict", "lax", and "skip"
</td></tr><tr><td valign="top">Identity‑Constraint Definition </td><td valign="top">the value
of the {identity-constraint category} property, one of "key",
"keyref", and "unique"</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">empty</td></tr><tr><td valign="top">Assertion</td><td valign="top">empty</td></tr><tr><td valign="top">Notation Declaration </td><td valign="top">empty</td></tr><tr><td valign="top">Annotation </td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">empty</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">the value of the
{variety} property, one of "atomic", "union", and "list"</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">the facet variety,
e.g. "minLength" for the minLength facet, and so on</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">the facet variety,
e.g. "numeric" for the numeric facet, and so on</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-component-children" name="accessor-component-children" />4.5.4 component-children Accessor</h4><p>The component-children accessor returns a sequence of schema components
consisting of all the components immediately accessible through default axes,
skipping minor components that produce no steps in the schema component path.
</p><table border="0" cellspacing="5" summary="component-children accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of component-children()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">the value of {type definition}</td></tr><tr><td valign="top">Element Declaration </td><td valign="top">the value of {type definition}</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">
the value of {attribute uses} and;
if the value of the component-variety() accessor is "empty" then empty,
if the value of the component-variety() accessor is "simple" then the value of
{simple type definition} (1.1) or the value of {content type} (1.0);
otherwise the value of the term() accessor
</td></tr><tr><td valign="top">Attribute Use </td><td valign="top">the value of {attribute declaration}</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">the
value {attribute declaration} for each Attribute Use in {attribute uses}
</td></tr><tr><td valign="top">Model Group Definition </td><td valign="top">the value of
{model group}</td></tr><tr><td valign="top">Model Group </td><td valign="top">the value of
the {term} of each Particle in {particles}</td></tr><tr><td valign="top">Particle</td><td valign="top">the value of {term}</td></tr><tr><td valign="top">Wildcard</td><td valign="top">empty</td></tr><tr><td valign="top">Identity‑Constraint Definition </td><td valign="top">empty</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">the value of {type definition}</td></tr><tr><td valign="top">Assertion</td><td valign="top">empty</td></tr><tr><td valign="top">Notation Declaration </td><td valign="top">empty</td></tr><tr><td valign="top">Annotation </td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">the value of {element declarations}</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">the value of {facets}</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">empty</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">empty</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-component-linked" name="accessor-component-linked" />4.5.5 component-linked Accessor</h4><p>The component-linked accessor returns a sequence of schema components
immediately accessible using any axis, skipping minor components that produce
no steps in the schema component path.
</p><table border="0" cellspacing="5" summary="component-linked accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of component-linked()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">
the value of the component-children() and annotations() accessors,
together with the {scope} (1.0) or the {parent} of {scope} (1.1)
</td></tr><tr><td valign="top">Element Declaration</td><td valign="top">
the value of the component-children() and annotations() accessors,
together with the value of {scope} and {substitution group affiliation}
(1.0) or the value of {substitution group affiliations}, the value of the
{parent} of {scope},
the value of the {alternatives} and {default type definition} of {type table}
(1.1), along with the value of {identity constraint definitions}
</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">
the value of component-children() and annotations() accessors,
together with the value of {base type definition}, {context},
{attribute wildcard}, and {assertions} and the value of {wildcard} of
{open content} of {content type}
</td></tr><tr><td valign="top">Attribute Use</td><td valign="top">
the value of the component-children() and annotations() accessors
</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">the
value of the component-children() and annotations() accessors,
as well as the value of {attribute wildcard}
</td></tr><tr><td valign="top">Model Group Definition </td><td valign="top">
the value of the component-children() and annotations() accessors
</td></tr><tr><td valign="top">Model Group</td><td valign="top">the value of
the component-children() and annotations() accessors</td></tr><tr><td valign="top">Particle</td><td valign="top">the value of the
component-children() accessor</td></tr><tr><td valign="top">Wildcard</td><td valign="top">the value of the
annotations() accessor</td></tr><tr><td valign="top">Identity‑Constraint Definition </td><td valign="top">the value of the annotations() accessor, together with the value
of {referenced key}</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">the value of
the component-childrenl() and annotations() accessors</td></tr><tr><td valign="top">Assertion</td><td valign="top">the value of the
annotations() accessor</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top">the value of
the annotations() accessor</td></tr><tr><td valign="top">Annotation</td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">
the value of the component-children() and annotations() accessors, as well as
the value of {type definitions}, {attribute declarations}, {attribute group
definitions}, {model group definitions}, {notation declarations}, and
{identity-constraint definitions}</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">the value of
the component-children() and annotations() accessors, together with the value
of {context}, {base type definition}, {fundamental facets}, {primitive type
definition}, {item type definition}, and {member type definitions}</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">the value of the
annotations() accessor, together with the value of {value} in the case that the
facet is the "assertions" facet</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">empty</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-term" name="accessor-term" />4.5.6 term Accessor</h4><p>The term accessor returns term components linked through the
{model group} or {term} arcs, possibly via {particle}, {particles}, or {content
type} arcs.</p><table border="0" cellspacing="5" summary="term accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of term()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Element Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">
the value of {term} of {particle} of {content type} (1.1) or the value of
{term} of {content type} (1.0),
together with the value of {wildcard} of
{open content} of {content type}
</td></tr><tr><td valign="top">Attribute Use</td><td valign="top">empty</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Model Group Definition</td><td valign="top">value of {model group}</td></tr><tr><td valign="top">Model Group</td><td valign="top">empty</td></tr><tr><td valign="top">Particle</td><td valign="top">the value of {term}</td></tr><tr><td valign="top">Wildcard</td><td valign="top">empty</td></tr><tr><td valign="top">Identity‑Constraint Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">empty</td></tr><tr><td valign="top">Assertion</td><td valign="top">empty</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Annotation</td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">empty</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">empty</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">empty</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-component-scope" name="accessor-component-scope" />4.5.7 component-scope Accessor</h4><p>The component-scope accessor returns components linked through the
{scope} possibly via {parent} arcs.</p><table border="0" cellspacing="5" summary="component-scope accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of component-context()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">
if component-variety() is "global" then empty; otherwise
the value of {parent} of {scope} (1.1) or the value of {scope} (1.0)
</td></tr><tr><td valign="top">Element Declaration</td><td valign="top">
if component-variety() is "global" then empty; otherwise
the value of {parent} of {scope} (1.1) or the value of {scope} (1.0)
</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Attribute Use</td><td valign="top">empty</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Model Group Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Model Group</td><td valign="top">empty</td></tr><tr><td valign="top">Particle</td><td valign="top">empty</td></tr><tr><td valign="top">Wildcard</td><td valign="top">empty</td></tr><tr><td valign="top">Identity‑Constraint Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">empty</td></tr><tr><td valign="top">Assertion</td><td valign="top">empty</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Annotation</td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">empty</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">empty</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">empty</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-assertions" name="accessor-assertions" />4.5.8 assertions Accessor</h4><p>The assertions accessor returns assertions components linked through the
{assertions} or {value} arcs. The assertions
accessor is always empty for the 1.0 schema component model.</p><table border="0" cellspacing="5" summary="assertions accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of assertions()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Element Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">the value of {assertions}</td></tr><tr><td valign="top">Attribute Use</td><td valign="top">empty</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Model Group Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Model Group</td><td valign="top">empty</td></tr><tr><td valign="top">Particle</td><td valign="top">empty</td></tr><tr><td valign="top">Wildcard</td><td valign="top">empty</td></tr><tr><td valign="top">Identity‑Constraint Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">empty</td></tr><tr><td valign="top">Assertion</td><td valign="top">empty</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top">empty</td></tr><tr><td valign="top">Annotation</td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">empty</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">empty</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">empty</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">empty unless
the facet name is "assertions"; the value of {value} otherwise</td></tr></tbody></table></div><div class="div3">
<h4><a id="accessor-annotations" name="accessor-annotations" />4.5.9 annotations Accessor</h4><p>The annotations accessor returns annotations components linked through the
{annotation} or {annotations} arc.
</p><table border="0" cellspacing="5" summary="annotations accessor details"><thead><tr><th align="left" valign="top">Component</th><th align="left" valign="top">Result of annotations()</th></tr></thead><tbody><tr><td valign="top">Attribute Declaration</td><td valign="top">the value of
{annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Element Declaration</td><td valign="top">the value of
{annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Complex Type Definition</td><td valign="top">
the value of {annotations}
</td></tr><tr><td valign="top">Attribute Use</td><td valign="top">the value of
{annotations}</td></tr><tr><td valign="top">Attribute Group Definition</td><td valign="top">the value of {annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Model Group Definition</td><td valign="top">the
value of {annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Model Group</td><td valign="top">the value of
{annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Particle</td><td valign="top">the value of {annotations}</td></tr><tr><td valign="top">Wildcard</td><td valign="top">the value of {annotation}
(1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Identity‑Constraint Definition</td><td valign="top">the value of {annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Type Alternative</td><td valign="top">the value of {annotations}</td></tr><tr><td valign="top">Assertion</td><td valign="top">the value of {annotations}</td></tr><tr><td valign="top">Notation Declaration</td><td valign="top">the value
of {annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Annotation</td><td valign="top">empty</td></tr><tr><td valign="top">Schema</td><td valign="top">the value of {annotations}</td></tr><tr><td valign="top">Simple Type Definition</td><td valign="top">the
value of {annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Constraining Facet</td><td valign="top">the value of
{annotation} (1.0) or {annotations} (1.1)</td></tr><tr><td valign="top">Fundamental Facet</td><td valign="top">empty</td></tr></tbody></table></div></div><div class="div2">
<h3><a id="section-canonical-path" name="section-canonical-path" />4.6 Canonical Schema Component Paths</h3><p>[<a title="canonical schema component path" id="key-canonical-schema-component-path" name="key-canonical-schema-component-path">Definition</a>: The <b>canonical schema
component path</b> of a component is a distinguished valid component path
that uniquely identifies that particular component, that has as few steps as
possible, and that can be deterministically constructed starting from the schema description component, and that contains no
extension axes or accessors.
]</p><p>The remainder of this section consists of a constructive definition of
canonical schema component paths: a path produced by this construction will be
the canonical one.</p><p>[<a title="current schema component" id="key-current-component" name="key-current-component">Definition</a>: The
    <b>current schema component</b> is a schema component for which
    there is a valid canonical path through the schema component graph.]</p><p>[<a title="target schema component" id="key-target-component" name="key-target-component">Definition</a>: The
    <b>target schema component</b> is a schema component linked to the
    current schema component via one of the schema component properties
    defined previously.]</p><p>[<a title="component relationship" id="key-component-relationship" name="key-component-relationship">Definition</a>: The
    <b>component relationship</b> is the name of the schema component
    property on the current schema component which references the target schema
    component.
]</p><p>[<a title="ancestor set" id="key-ancestor-set" name="key-ancestor-set">Definition</a>: The
    <b>ancestor set</b> of the target schema component is the set of schema
    components on the valid canonical path to the current schema component
    together with the current schema component.]</p><p>[<a title="base type set" id="key-base-type-set" name="key-base-type-set">Definition</a>:
The <b>base type set</b> of a schema component is the set
consisting of the {base type definition} of that schema component and
the {base type definition} of every member of the set.
]</p><p>Constructively,  this set can be computed by adding the
{base type definition} to the set, and iterating on that type component, until
you see a component whose {target namespace} property is
"http://www.w3.org/2001/XMLSchema" and whose {name} property is
"anyType".
</p><p>[<a title="extended base type set" id="key-extended-base-type-set" name="key-extended-base-type-set">Definition</a>: The <b>extended base type
set</b> of a schema component is
the set consisting of the {base type definition} of that schema component if
its {derivation} method is "extension" and the {base type definition} of
every member of the set whose {derivation} method is "extension".
]
</p><p>[<a title="base facet set" id="key-base-facet-set" name="key-base-facet-set">Definition</a>: The <b>base facet set</b> of a schema
component is the set consisting of all members of the {facets} property of
members of the base type set of that schema component.]
</p><p>[<a title="same (facets)" id="key-same-facet" name="key-same-facet">Definition</a>: Two facets are <b>the same</b> if they
are the same kind of component (e.g. both are length facets) and their {value}
properties have identical values.]</p><p>[<a title="base attribute use set" id="key-base-attribute-use-set" name="key-base-attribute-use-set">Definition</a>: The <b>base attribute use
set</b> of a schema component is the set consisting of all members of the
{attribute uses} property of members of the base type set of that schema
component.]
</p><p>[<a title="same (attribute uses)" id="key-same-attr-uses" name="key-same-attr-uses">Definition</a>: Two attribute uses are <b>the
same</b> if the {name} and {target namespace} of their {attribute
declaration} properties are equal. ]
</p><p>(Note that this is not equality which requires checking the {type definition}
as well. However, the rules for component consistency will ensure that
checking the {name} and {target namespace} suffices for our purposes here.)
</p><p>[<a title="particle set" id="key-particle-set" name="key-particle-set">Definition</a>: The <b>particle set</b> of a schema
component is the set consisting
of the {content type} of that schema component with the members of the
{particles} property of the {term} of any member of the set.]
</p><p>[<a title="base particle set" id="key-base-particle-set" name="key-base-particle-set">Definition</a>: The <b>base particle set</b> of a
schema component is the union of all particle sets of all the members of the
extended base type set of that schema component.]
</p><p>[<a title="same (particles)" id="key-same-particle" name="key-same-particle">Definition</a>: Two particles are <b>the same</b> if
the implementation reports them as the same.] Informally,
implementations will report particles that are "inherited" from base types as
"the same" as the corresponding particle in the base type. Future revisions of
the XML Schema recommendation will specify more precisely the conditions under
which particles should be regarded as "the same".
</p><p>Traversal where the current schema component
    is the schema description
component to any target schema component
    is always permitted in the construction of a
canonical path. If the current schema component is not the schema description
schema component, then traversal from the current schema component
to the target schema component is forbidden in the construction of a canonical
path if any of the following conditions is met:</p><ol class="enumar"><li><p>the target schema component is an identity constraint definition</p></li><li><p>the target schema component is a simple or complex type
definition whose {name} property is not absent</p></li><li><p>the target schema component is an element or attribute declaration
whose {scope} property is <code>global</code></p></li><li><p>the target schema component has a {scope} property whose value is a
schema component and that schema component is not a member of the
ancestor set of the target schema component</p></li><li><p>the component relationship is {scope},
{substitution group affiliation},
{primitive type definition}, or {referenced key}</p></li><li><p>the component relationship is {base type definition}
and target schema component's {name} property is not absent</p></li><li><p>the target schema component is a facet and there exists some facet in
its base facet set of the target schema component that is the same as the
facet</p></li><li><p>the current schema component is a complex type, the target schema
component is the {attribute declaration} of an attribute use component and there
exists some attribute use in the base attribute use set of the current
schema component that is the same as the attribute use whose {attribute
declaration} is the target schema component</p></li><li><p>the target schema component is the {term} of a particle and there
exists some particle in the base particle set of the current schema component
that  is the same as the target schema component</p></li></ol><p>Informally, the first two conditions ensure that the canonical path to
an identity constraint or a named type is the one that flows directly from the
schema description component, the third condition ensures that the canonical
path to element and attribute declarations is likewise the global one (if there
is one), the fourth
condition accounts for element and attribute declarations stemming from named
model groups and attribute groups, the fifth and sixth ensure that the
canonical path doesn't follow "backwards" paths (while accounting for
redefined types), and the final three
conditions ensure the canonical path to "inherited" components goes
through their component of origin.</p><p>Because the 1.0 component model provides no reliable
ordering of annotations, selection of a specific annotation using a numerical
predicate is forbidden in canonical paths against a 1.0 schema.  For 1.1
schemas, an individual annotation component is selected using a numerical
predicate.</p><p>In general, it is not possible to obtain the canonical path for a
schema component without access to the schema component graph. In particular,
canonicalizing some non-canonical path, or determining whether a schema
component path is canonical cannot be performed without such access.
</p><p>For example, consider the path
<code>/type::x:foo/schemaElement::x:bar</code>.
</p><p>For this schema fragment, this represents a canonical path to the local
element <code>bar</code>:</p><div class="exampleInner"><pre>
&lt;complexType name="foo"&gt;
  &lt;sequence&gt;
     &lt;element name="bar" type="x:barType"/&gt;
  &lt;/sequence&gt;
&lt;/complexType&gt;
</pre></div><p>But for the following schema fragment,
the same path
represents a non-canonical path. The
canonical path would instead be <code>/group::x:barGroup/schemaElement::x:bar</code>.
</p><div class="exampleInner"><pre>
&lt;group name="barGroup"&gt;
  &lt;sequence&gt;
     &lt;element name="bar" type="x:barType"/&gt;
  &lt;/sequence&gt;
&lt;/group&gt;
&lt;complexType name="foo"&gt;
  &lt;sequence&gt;
    &lt;group ref="x:barGroup"/&gt;
  &lt;/sequence&gt;
&lt;/complexType&gt;
</pre></div><div class="div3">
<h4><a id="section-canonical-syntax" name="section-canonical-syntax" />4.6.1 Canonical Syntax</h4><p>The concrete syntax allows certain abbreviations, such as
        eliding the positional predicate where it is
        unnecessary to distinguish components,
        wildcarded schema component name tests
        (<code>*</code>), and abbreviated steps
        (e.g. <code>@name</code>)
        .
        Canonical path syntax forbids all these abbreviations. In addition, the
        canonical path syntax fixes the namespace prefix, if any, to
        <code>p</code>. Since at most one namespace can be involved in a
        canonical schema component path, one prefix suffices.
        Finally, use of the current component, component, and
        elided-component axes are disallowed in the canonical path
        syntax, and the use of the particle and attributeUse axes are
        disallowed except in the last step of the path.
        </p></div></div><div class="div2">
<h3><a id="section-equality-path" name="section-equality-path" />4.7 Equality of Schema Component Paths</h3><p>[<a title="schema component paths are equal" id="key-equal-path" name="key-equal-path">Definition</a>: Two <b>schema component paths are
equal</b> if they have the same number of
steps, and each step in one path is equal to the corresponding
step in the other. Steps are equal if they have the same
axis, name test (namespace and local name, or wildcard), and predicate.
.]
</p><p>Note: This definition of equality neither relies on the notion of 'the same
component' nor defines component equivalence. A schema component may have
multiple schema component paths. Although these schema component paths address
'the same component', they are not equal. It is true, however, that two
canonical paths to the same component will be equal.</p></div></div><div class="div1">
<h2><a id="section-conformance" name="section-conformance" />5 Conformance</h2><div class="div2">
<h3><a id="scp-conformance" name="scp-conformance" />5.1 Schema Component Path Conformance</h3><p>Schema component paths may be used by other specifications.
For such usage, this specification does not define any criteria
for conformance and relies on other specifications to specify
criteria for conformance of implementations.
</p><p>Such specifications must define:
</p><ul><li><p>How the target schema is identified.</p></li><li><p>How namespace binding applies to schema component paths, in particular
how or whether the default namespace applies.</p></li><li><p>Whether only canonical schema component paths are
permitted.</p></li><li><p>Whether only complete schema component paths are permitted.</p></li><li><p>If incomplete schema component paths are permitted, how the initial
source component is determined.</p></li><li><p>Whether any extension axes are defined, together with their syntax
and semantics.</p></li><li><p>Whether any extension accessors are defined, together with their
syntax and semantics.</p></li></ul></div><div class="div2">
<h3><a id="scds-conformance" name="scds-conformance" />5.2 Schema Component Designator Conformance</h3><p>
This specification normatively depends on the XPointer Framework
<a href="#xptrframework">[XPTR]</a>.
</p><p>Conforming XPointer processors claiming to support the
<code>xscd()</code> scheme must
identify schema components as
defined in this specification and
conform to the XPointer <code>xmlns()</code> scheme
specification.
</p></div><div class="div2">
<h3><a id="N1136D" name="N1136D" />5.3 Extensibility</h3><p>Schema component paths and designators navigate the XML Schema component
model and are wholly dependent on that model to define the set of allowable
axes and referenced components.  Therefore, as the schema component model
changes, this specification may add additional axes, mapping rules, and
accessors as required to support those changes.
The EBNF defines syntax for extension accessors after the last step in a path
and for extension axes.
</p></div></div><div class="div1">
<h2><a id="section-example" name="section-example" />6 Examples (Non-Normative)</h2><div class="div2">
<h3><a id="section-primer-example" name="section-primer-example" />6.1 Extended Primer Example</h3><p>This section walks through an example XML Schema Document from the XML
Schema Part 0: Primer<a href="#xsd0">[XSD0]</a> and
  enumerates the abbreviated and canonical schema component designators for schema components.</p><p>All schema constructs in this section are considered to be in the following
  schema document and its URI is <code>schema-URI</code>:</p><div class="exampleInner"><pre>
&lt;xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"&gt;
&lt;!-- elided... see below ... --&gt;
&lt;/xsd:schema&gt;
</pre></div><p>Since this schema has no target namespace, no namespace
  binding is required and there is no <code>xmlns()</code> pointer part for any
  of the schema component designators for this schema.</p><p>The canonical schema component designator for this schema description
component is <code>schema-URI#xscd(/)</code>.</p><div class="exampleInner"><pre>
&lt;xsd:annotation&gt;
 &lt;xsd:documentation xml:lang="en"&gt;
  Purchase order schema for Example.com.
  Copyright 2000 Example.com. All rights reserved.
 &lt;/xsd:documentation&gt;
&lt;/xsd:annotation&gt;
</pre></div><p>The canonical schema component designator for this annotation schema component
  is <code>schema-URI#xscd(/annotation::*)</code>.</p><p>The following is a global element declaration:</p><div class="exampleInner"><pre>
&lt;xsd:element name="purchaseOrder" type="PurchaseOrderType"/&gt;
</pre></div><p>The abbreviated schema component designator for this element declaration component
  is <code>schema-URI#xscd(/purchaseOrder)</code> and the canonical is
  <code>schema-URI#xscd(/schemaElement::purchaseOrder)</code>.</p><p>The following is another global element declaration, </p><div class="exampleInner"><pre>
 &lt;xsd:element name="comment" type="xsd:string"/&gt;
</pre></div><p>The abbreviated schema component designator for this element declaration
  component is <code>schema-URI#xscd(/comment)</code> and the canonical is
  <code>schema-URI#xscd(/schemaElement::comment)</code>.</p><p>This following is a global complex type definition component:</p><div class="exampleInner"><pre>
&lt;xsd:complexType name="PurchaseOrderType"&gt;
 &lt;xsd:sequence&gt;
  &lt;xsd:element name="shipTo" type="USAddress"/&gt;
  &lt;xsd:element name="billTo" type="USAddress"/&gt;
  &lt;xsd:element ref="comment" minOccurs="0"/&gt;
  &lt;xsd:element name="items"  type="Items"/&gt;
 &lt;/xsd:sequence&gt;
 &lt;xsd:attribute name="orderDate" type="xsd:date"/&gt;
&lt;/xsd:complexType&gt;
</pre></div><p>The abbreviated schema component designator for this complex type definition
  and its element and attribute declaration components are:</p><div class="exampleInner"><pre>
schema-URI#xscd(/~purchaseOrderType)
schema-URI#xscd(/~purchaseOrderType/shipTo)
schema-URI#xscd(/~purchaseOrderType/billTo)
schema-URI#xscd(/comment)
schema-URI#xscd(/~purchaseOrderType/items)
schema-URI#xscd(/~purchaseOrderType/@orderDate)
</pre></div><p>The canonical schema component designator for this complex type definition and
  its element and attribute declaration components are:</p><div class="exampleInner"><pre>
schema-URI#xscd(/type::purchaseOrderType)
schema-URI#xscd(/type::purchaseOrderType/model::sequence/schemaElement::shipTo)
schema-URI#xscd(/type::purchaseOrderType/model::sequence/schemaElement::billTo)
schema-URI#xscd(/schemaElement::comment)
schema-URI#xscd(/type::purchaseOrderType/model::sequence/schemaElement::items)
schema-URI#xscd(/type::purchaseOrderType/schemaAttribute::orderDate)
</pre></div><p>The following is another global complex type definition component:</p><div class="exampleInner"><pre>
&lt;xsd:complexType name="USAddress"&gt;
 &lt;xsd:sequence&gt;
  &lt;xsd:element name="name"   type="xsd:string"/&gt;
  &lt;xsd:element name="street" type="xsd:string"/&gt;
  &lt;xsd:element name="city"   type="xsd:string"/&gt;
  &lt;xsd:element name="state"  type="xsd:string"/&gt;
  &lt;xsd:element name="zip"    type="xsd:decimal"/&gt;
 &lt;/xsd:sequence&gt;
 &lt;xsd:attribute name="country" type="xsd:NMTOKEN"
     fixed="US"/&gt;
&lt;/xsd:complexType&gt;
</pre></div><p>The abbreviated schema component designator for this complex type definition
  and its element and attribute declaration components are:</p><div class="exampleInner"><pre>
schema-URI#xscd(/~USAddress)
schema-URI#xscd(/~USAddress/name)
schema-URI#xscd(/~USAddress/street)
schema-URI#xscd(/~USAddress/city)
schema-URI#xscd(/~USAddress/state)
schema-URI#xscd(/~USAddress/zip)
schema-URI#xscd(/~USAddress/@country)
</pre></div><p>The canonical schema component designator for this complex type definition and its
  element and attribute declaration components are:</p><div class="exampleInner"><pre>
schema-URI#xscd(/type::USAddress)
schema-URI#xscd(/type::USAddress/model::sequence/schemaElement::name)
schema-URI#xscd(/type::USAddress/model::sequence/schemaElement::street)
schema-URI#xscd(/type::USAddress/model::sequence/schemaElement::city)
schema-URI#xscd(/type::USAddress/model::sequence/schemaElement::state)
schema-URI#xscd(/type::USAddress/model::sequence/schemaElement::zip)
schema-URI#xscd(/type::USAddress/schemaAttribute::country)
</pre></div><p>The following is a global complex type definition with anonymous complex type and
  simple type definition components:</p><div class="exampleInner"><pre>
&lt;xsd:complexType name="Items"&gt;
 &lt;xsd:sequence&gt;
  &lt;xsd:element name="item" minOccurs="0" maxOccurs="unbounded"&gt;
   &lt;xsd:complexType&gt;
    &lt;xsd:sequence&gt;
     &lt;xsd:element name="productName" type="xsd:string"/&gt;
     &lt;xsd:element name="quantity"&gt;
      &lt;xsd:simpleType&gt;
       &lt;xsd:restriction base="xsd:positiveInteger"&gt;
        &lt;xsd:maxExclusive value="100"/&gt;
       &lt;/xsd:restriction&gt;
      &lt;/xsd:simpleType&gt;
     &lt;/xsd:element&gt;
     &lt;xsd:element name="USPrice"  type="xsd:decimal"/&gt;
     &lt;xsd:element ref="comment"   minOccurs="0"/&gt;
     &lt;xsd:element name="shipDate" type="xsd:date" minOccurs="0"/&gt;
    &lt;/xsd:sequence&gt;
    &lt;xsd:attribute name="partNum" type="SKU" use="required"/&gt;
   &lt;/xsd:complexType&gt;
  &lt;/xsd:element&gt;
 &lt;/xsd:sequence&gt;
&lt;/xsd:complexType&gt;
</pre></div><p>The abbreviated schema component designator for this complex type definition
  and its element and attribute declaration, simple type definition, and facet
  components are:</p><div class="exampleInner"><pre>
schema-URI#xscd(/~Items)
schema-URI#xscd(/~Items/item)
schema-URI#xscd(/~Items/item/~0))
schema-URI#xscd(/~Items/item/productName)
schema-URI#xscd(/~Items/item/quantity)
schema-URI#xscd(/~Items/item/quantity/~0)
schema-URI#xscd(/~Items/item/quantity/~0/facet::maxExclusive)
schema-URI#xscd(/~Items/item/USPrice)
schema-URI#xscd(/comment)
schema-URI#xscd(/~Items/item/shipDate)
schema-URI#xscd(/~Items/item/@partNum)
</pre></div><p>The canonical schema component designator for this complex type definition and its
element and attribute declaration, simple type definition, and facet
components are (paths broken across lines for
readability):</p><div class="exampleInner"><pre>
schema-URI#xscd(/type::Items)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     model::sequence/schemaElement::productName)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     model::sequence/schemaElement::quantity)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     model::sequence/schemaElement::quantity/type::0)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     model::sequence/schemaElement::quantity/type::0/
     facet::maxExclusive)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     model::sequence/schemaElement::USPrice)
schema-URI#xscd(/schemaElement::comment)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     model::sequence/schemaElement::shipDate)
schema-URI#xscd(/type::Items/model::sequence/schemaElement::item/type::0/
     schemaAttribute::partNum)
</pre></div><p>The following is a global simple type definition component:</p><div class="exampleInner"><pre>
&lt;!-- Stock Keeping Unit, a code for identifying products --&gt;
&lt;xsd:simpleType name="SKU"&gt;
 &lt;xsd:restriction base="xsd:string"&gt;
  &lt;xsd:pattern value="\d{3}-[A-Z]{2}"/&gt;
 &lt;/xsd:restriction&gt;
&lt;/xsd:simpleType&gt;
</pre></div><p>The canonical schema component designator for this simple type definition
  and its facet component are:</p><div class="exampleInner"><pre>
schema-URI#xscd(/type::SKU)
schema-URI#xscd(/type::SKU/facet::pattern)
</pre></div></div><div class="div2">
<h3><a id="section-example-more" name="section-example-more" />6.2 Additional Examples</h3><p>The schema for the examples in the previous section had no
target namespace. If we change the schema so that the target namespace is
<code>"http://example.com/schema/po"</code>, then the schema
component designators need to take namespace bindings into account.
</p><p>For example, the abbreviated schema component designator for the
complex type definition <code>USAddress</code> and its element and attribute
declaration components are:</p><div class="exampleInner"><pre>
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress/p:name)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress/p:street)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress/p:city)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress/p:state)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress/p:zip)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/~p:USAddress/@country)
</pre></div><p>Note that since the <code>attributeFormDefault</code> for the
schema is <code>unqualified</code> (the default value), no namespace prefix is
used with the <code>country</code> attribute.</p><p>The canonical schema component designator for this complex type
definition and its element and attribute declaration components are (paths
broken across lines for readability):</p><div class="exampleInner"><pre>
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress/
    model::sequence/schemaElement::p:name)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress/
    model::sequence/schemaElement::p:street)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress/
    model::sequence/schemaElement::p:city)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress/
    model::sequence/schemaElement::p:state)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress/
    model::sequence/schemaElement::p:zip)
schema-URI#xmlns(p=http://example.com/schema/po)xscd(/type::p:USAddress/
    schemaAttribute::country)
</pre></div><p>Schema component paths may also be used in other contexts that
provide namespace binding contexts.  For example, an XML representation may
apply normal namespace binding rules to apply to embedded schema component
paths:
</p><div class="exampleInner"><pre>
&lt;xsx:ui xmlns:err="http://example.com/extension/ui"
        xmlns:p="http://example.com/schema/po"&gt;
  &lt;xsx:component&gt;
     &lt;xsx:path&gt;/~p:USAddress/p:state&lt;/xsx:path&gt;
     &lt;xsx:prompt&gt;State&lt;/xsx:prompt&gt;
     &lt;xsx:display&gt;selector&lt;/xsx:display&gt;
     &lt;xsx:choices&gt;http://example.com/state-menu.xml&lt;/xsx:choices&gt;
     &lt;xsx:tab&gt;Address&lt;/xsx:tab&gt;
  &lt;/xsx:component&gt;
&lt;/xsx:ui&gt;
</pre></div><p>Another possible means of binding namespaces is to use the namespace URI as
the schema designator with the convention that it is the default namespace.
This could be useful combined with the use of just the schema component paths
in the fragment identifier to obtain terse identifiers for global schema types
in single-namespace schemas:
</p><div class="exampleInner"><pre>
http://www.w3.org/2001/XMLSchema#/~gMonth
</pre></div><div class="note"><p class="prefix"><b>Note:</b></p><p>This specification does not define such a fragment identifier scheme
for namespace documents.  Neither does it rule out such a usage.
</p></div></div><div class="div2">
<h3><a id="section-examples-abbreviations" name="section-examples-abbreviations" />6.3 Examples with component and elided-component Axes (Non-Normative)</h3><p>The following examples assume that the namespace prefixes
<code>r</code> and <code>ipo</code> are appropriately bound.</p><p>Here is a path that designates an attribute declaration whose local name is
<code>period</code> in the namespace denoted by
<code>r</code> in an anonymous complex type:
</p><div class="exampleInner"><pre>/r:purchaseReport/type::0/@period</pre></div><p>Using the
elided-component axis to select the attribute
declaration directly from the element declaration, this path reduces to:
</p><div class="exampleInner"><pre>/r:purchaseReport/@period</pre></div><p>Here is a path that designates an
element
declaration whose local name is
<code>name</code> in the namespace denoted by
<code>ipo</code>
in a globally defined type:
</p><div class="exampleInner"><pre>/type::ipo:USAddress/model::sequence/model::sequence[1]/name</pre></div><p>
Using the elided-component axis to select the element
declaration directly from the complex type definition,
this path reduces to:</p><div class="exampleInner"><pre>/type::ipo:USAddress/name</pre></div><p>This path designates an element declaration whose local name is
<code>regions</code>
in the namespace denoted by
<code>r</code>
in an anonymous complex type:
</p><div class="exampleInner"><pre>/r:purchaseReport/type::0/model::sequence/r:regions</pre></div><p>Using the elided-component axis to select
the element declaration r:regions directly from the element declaration
r:purchaseReport, this path reduces to:</p><div class="exampleInner"><pre>/r:purchaseReport/r:regions</pre></div><p>This path
designates global or local element declarations whose local
name is <code>quantity</code> in the namespace denoted by <code>r</code>:</p><div class="exampleInner"><pre>//r:quantity</pre></div><p>This path designates global or local element declarations whose
local name is <code>quantity</code> in the namespace denoted
by <code>r</code>, where these declarations
are in the subgraph represented by the global complex type component whose
local name is <code>Items</code> in the namespace denoted by
<code>r</code>:
</p><div class="exampleInner"><pre>/~r:Items//r:quantity</pre></div><p>This path designates global or local attribute
declarations whose local name is <code>partNum</code> in the
namespace denoted by <code>r</code>
where these declarations are in the subgraph represented by the global complex
type component whose
local name is <code>Items</code>
in the namespace denoted by <code>r</code>:</p><div class="exampleInner"><pre>/~r:Items//@partNum</pre></div><p>This extended example works against the following schema
  fragment for a schema with no target namespace:
</p><div class="exampleInner"><pre>
&lt;xs:element name="example" type="aType"/&gt;

&lt;xs:complexType name="aType"&gt;
   &lt;xs:sequence&gt;
      &lt;xs:element name="foo"/&gt;
      &lt;xs:group ref="aGroup"/&gt;
   &lt;/xs:sequence&gt;
&lt;/xs:complexType&gt;

&lt;xs:group name="aGroup"&gt;
   &lt;xs:sequence&gt;
      &lt;xs:element name="bar"&gt;
         &lt;xs:complexType&gt;
           &lt;xs:sequence&gt;
              &lt;xs:element ref="foo"/&gt;
              &lt;xs:element ref="a"/&gt;
           &lt;/xs:sequence&gt;
         &lt;/xs:complexType&gt;
      &lt;/xs:element&gt;
   &lt;/xs:sequence&gt;
&lt;/xs:group&gt;

&lt;xs:element name="foo"/&gt;
</pre></div><p>
Which of the following paths can be shortened to <code>//foo</code> using the
component and elided-component axes?
</p><table border="0" cellspacing="5" summary="//foo"><thead><tr><th>Path</th><th>Shortened to <code>//foo</code>?</th></tr></thead><tbody><tr><td><code>/group::aGroup/model::sequence/bar/~0/model::sequence/foo</code></td><td>No</td></tr><tr><td><code>/~aType/model::sequence/foo</code></td><td>Yes</td></tr><tr><td><code>/~aType/model::sequence/model::sequence/bar/~0/foo</code></td><td>No</td></tr><tr><td><code>/root/~aType/model::sequence/foo</code></td><td>Yes</td></tr><tr><td><code>/root/~aType/model::sequence/model::sequence/bar/~0/foo</code></td><td>No</td></tr></tbody></table><p>The "no" answers are all because <code>bar</code> is not selected
by either the component axis or the elided-component axis and must therefore
appear in the path.</p></div></div></div><div class="back"><div class="div1">
<h2><a id="properties" name="properties" />A Schema Component Properties (Non-Normative)</h2><p>Schema component paths rely on the schema component graph implicit in
the assembled collection of schema components and their properties. The
following table details which properties are used for defining schema component
paths, and whether they are used to define links in the graph
(traversed) or just referenced for some other purpose. Traversals marked with a
star (*) are the default axis of traversal.
</p><table border="2" rules="rows" cellspacing="5" cellpadding="5" summary="Use of Schema Component Properties"><thead><tr><th>Component or Property Record</th><th>Property</th><th>Use</th></tr></thead><tbody><tr><th rowspan="8">Attribute Declaration</th></tr><tr><td>{type definition}</td><td>traversed *</td></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr><tr><td>{scope}</td><td>traversed</td></tr><tr><td>{value constraint}</td><td>none</td></tr></tbody><tbody><tr><th rowspan="3">Scope Property Record</th></tr><tr><td>{variety}</td><td>referenced</td></tr><tr><td>{parent}</td><td>traversed</td></tr></tbody><tbody><tr><th rowspan="16">Element Declaration</th></tr><tr><td>{type definition}</td><td>traversed *</td></tr><tr><td>{identity-constraint definitions}</td><td>traversed</td></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr><tr><td>{type table}</td><td>traversed</td></tr><tr><td>{scope}</td><td>traversed</td></tr><tr><td>{value constraint}</td><td>none</td></tr><tr><td>{nillable}</td><td>none</td></tr><tr><td>{substitution group affiliation}</td><td>traversed</td></tr><tr><td>{substitution group affiliations}</td><td>traversed</td></tr><tr><td>{substitution group exclusions}</td><td>none</td></tr><tr><td>{disallowed substitutions}</td><td>none</td></tr><tr><td>{abstract}</td><td>none</td></tr></tbody><tbody><tr><th rowspan="3">Type Table Property Record</th></tr><tr><td>{alternatives}</td><td>traversed</td></tr><tr><td>{default type definition}</td><td>traversed</td></tr></tbody><tbody><tr><th rowspan="14">Complex Type Definition</th></tr><tr><td>{base type definition}</td><td>traversed</td></tr><tr><td>{attribute uses}</td><td>traversed</td></tr><tr><td>{attribute wildcard}</td><td>traversed</td></tr><tr><td>{content type}</td><td>traversed *</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr><tr><td>{context}</td><td>traversed</td></tr><tr><td>{derivation method}</td><td>none</td></tr><tr><td>{final}</td><td>none</td></tr><tr><td>{abstract}</td><td>none</td></tr><tr><td>{prohibited substitutions}</td><td>none</td></tr><tr><td>{assertions}</td><td>traversed</td></tr></tbody><tbody><tr><th rowspan="5">Content Type Property Record</th></tr><tr><td>{variety}</td><td>referenced</td></tr><tr><td>{particle}</td><td>traversed *</td></tr><tr><td>{simple type definition}</td><td>traversed</td></tr><tr><td>{open content}</td><td>traversed</td></tr></tbody><tbody><tr><th rowspan="3">Open Content Property Record</th></tr><tr><td>{mode}</td><td>none</td></tr><tr><td>{wildcard}</td><td>traversed *</td></tr></tbody><tbody><tr><th rowspan="5">Attribute Use</th></tr><tr><td>{attribute declaration}</td><td>traversed *</td></tr><tr><td>{value constraint}</td><td>none</td></tr><tr><td>{required}</td><td>none</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr></tbody><tbody><tr><th rowspan="7">Attribute Group Definition</th></tr><tr><td>{attribute uses}</td><td>traversed *</td></tr><tr><td>{attribute wildcard}</td><td>traversed</td></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr></tbody><tbody><tr><th rowspan="6">Model Group Definition</th></tr><tr><td>{model group}</td><td>traversed *</td></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr></tbody><tbody><tr><th rowspan="5">Model Group</th></tr><tr><td>{particles}</td><td>traversed *</td></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{compositor}</td><td>referenced</td></tr></tbody><tbody><tr><th rowspan="5">Particle</th></tr><tr><td>{term}</td><td>traversed *</td></tr><tr><td>{min occurs}</td><td>none</td></tr><tr><td>{max occurs}</td><td>none</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr></tbody><tbody><tr><th rowspan="5">Wildcard</th></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{namespace constraint}</td><td>none</td></tr><tr><td>{process contents}</td><td>none</td></tr></tbody><tbody><tr><th rowspan="9">Identity-constraint Definition</th></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr><tr><td>{identity-constraint category}</td><td>none</td></tr><tr><td>{selector}</td><td>none</td></tr><tr><td>{fields}</td><td>none</td></tr><tr><td>{referenced key}</td><td>traversed</td></tr></tbody><tbody><tr><th rowspan="4">Type Alternative</th></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{test}</td><td>none</td></tr><tr><td>{type definition}</td><td>traversed *</td></tr></tbody><tbody><tr><th rowspan="3">Assertion</th></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{test}</td><td>none</td></tr></tbody><tbody><tr><th rowspan="7">Notation Declaration</th></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr><tr><td>{public identifier}</td><td>none</td></tr><tr><td>{system identifier}</td><td>none</td></tr></tbody><tbody><tr><th rowspan="4">Annotation</th></tr><tr><td>{application information}</td><td>none</td></tr><tr><td>{user information}</td><td>none</td></tr><tr><td>{attributes}</td><td>none</td></tr></tbody><tbody><tr><th rowspan="9">Schema</th></tr><tr><td>{type definitions}</td><td>traversed</td></tr><tr><td>{attribute declarations}</td><td>traversed</td></tr><tr><td>{element declarations}</td><td>traversed *</td></tr><tr><td>{attribute group definitions}</td><td>traversed</td></tr><tr><td>{model group definitions}</td><td>traversed</td></tr><tr><td>{notation declarations}</td><td>traversed</td></tr><tr><td>{identity constraint definitions}</td><td>traversed</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr></tbody><tbody><tr><th rowspan="14">Simple Type Definition</th></tr><tr><td>{base type definition}</td><td>traversed</td></tr><tr><td>{facets}</td><td>traversed *</td></tr><tr><td>{fundamental facets}</td><td>traversed</td></tr><tr><td>{item type definition}</td><td>traversed</td></tr><tr><td>{member type definitions}</td><td>traversed</td></tr><tr><td>{context}</td><td>traversed</td></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{name}</td><td>referenced</td></tr><tr><td>{target namespace}</td><td>referenced</td></tr><tr><td>{variety}</td><td>referenced</td></tr><tr><td>{final}</td><td>none</td></tr><tr><td>{primitive type definition}</td><td>traversed</td></tr></tbody><tbody><tr><th rowspan="5">Facets</th></tr><tr><td>{annotation}</td><td>traversed (special)</td></tr><tr><td>{annotations}</td><td>traversed (special)</td></tr><tr><td>{value}</td><td>traversed * (assertions only)</td></tr><tr><td>{fixed}</td><td>none</td></tr></tbody></table></div><div class="div1">
<h2><a id="axis-summary" name="axis-summary" />B Summary of Component Axes (Non-Normative)</h2><p>The following table details all the axes, the source and target component
kinds, a brief syntax summary, and indicates whether the axis is a default one.
</p><table border="2" rules="rows" cellspacing="5" cellpadding="5" summary="Summary of Component Axes"><thead><tr><th>Axis</th><th>Source Component</th><th>Target Component</th><th>Syntax</th><th>Default?</th></tr></thead><tbody><tr><th rowspan="2">(root)</th></tr><tr><td>N/A</td><td>Schema</td><td>/</td><td>no</td></tr></tbody><tbody><tr><th rowspan="11">annotations</th></tr><tr><td>Attribute Declaration</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Attribute Group Definition</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Element Declaration</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Facet</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Model Group Definition</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Notation Declaration</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Schema</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Simple Type Definition</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr><tr><td>Wildcard</td><td>Annotation</td><td><code>annotation::*</code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="3">attribute declarations</th></tr><tr><td>Attribute Use</td><td>Attribute Declaration</td><td><code>schemaAttribute::<var>qname</var></code></td><td>yes</td></tr><tr><td>Schema</td><td>Attribute Declaration</td><td><code>schemaAttribute::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">attribute group definitions</th></tr><tr><td>Schema</td><td>Attribute Group Definition</td><td><code>attributeGroup::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="3">attribute uses</th></tr><tr><td>Complex Type Definition</td><td>Attribute Use</td><td>N/A</td><td>no</td></tr><tr><td>Attribute Group Definition</td><td>Attribute Use</td><td>N/A</td><td>yes</td></tr></tbody><tbody><tr><th rowspan="3">attribute wildcard</th></tr><tr><td>Complex Type Definition</td><td>Attribute Wildcard</td><td><code>anyAttribute::*</code></td><td>no</td></tr><tr><td>Attribute Group Definition</td><td>Attribute Wildcard</td><td><code>anyAttribute::*</code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="4">base type definition</th></tr><tr><td rowspan="2">Complex Type Definition</td><td>Simple Type Definition</td><td><code>baseType::<var>qname</var></code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td><code>baseType::<var>qname</var></code></td><td>no</td></tr><tr><td>Simple Type Definition</td><td>Simple Type Definition</td><td><code>baseType::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">content type</th></tr><tr><td>Complex Type Definition</td><td>Complex Type Definition</td><td><code>type::<var>qname</var></code></td><td>yes</td></tr></tbody><tbody><tr><th rowspan="2">element declarations</th></tr><tr><td>Schema</td><td>Element Declaration</td><td><code>schemaElement::<var>qname</var></code></td><td>yes</td></tr></tbody><tbody><tr><th rowspan="2">facets</th></tr><tr><td>Simple Type Definition</td><td>Facet</td><td><code>facet::<var>name</var></code></td><td>yes</td></tr></tbody><tbody><tr><th rowspan="2">fundamental facets</th></tr><tr><td>Simple Type Definition</td><td>Fundamental Facet</td><td><code>facet::<var>name</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="3">identity constraint definitions</th></tr><tr><td>Element Declaration</td><td>Identity-constraint Definition</td><td><code>identityConstraint::<var>qname</var></code></td><td>no</td></tr><tr><td>Schema</td><td>Identity-constraint Definition</td><td><code>identityConstraint::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">item type definition</th></tr><tr><td>Simple Type Definition</td><td>Simple Type Definition</td><td><code>itemType::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">member type definitions</th></tr><tr><td>Simple Type Definition</td><td>Simple Type Definition</td><td><code>memberType::<var>qname</var></code>[n]</td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">model group</th></tr><tr><td>Model Group Definition</td><td>Model Group</td><td><code>model::<var>compositor</var>[<var>n</var>]</code></td><td>yes</td></tr></tbody><tbody><tr><th rowspan="2">model group definitions</th></tr><tr><td>Schema</td><td>Model Group Definition</td><td><code>group::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">notation declarations</th></tr><tr><td>Schema</td><td>Notation Declaration</td><td><code>notation::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">particles</th></tr><tr><td>Model Group</td><td>Particle</td><td>N/A</td><td>yes</td></tr></tbody><tbody><tr><th rowspan="2">primitive type definition</th></tr><tr><td>Simple Type Definition</td><td>Simple Type Definition</td><td><code>primitivetype::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">referenced key</th></tr><tr><td>Identity-constraint Definition</td><td>Identity-constraint Definition</td><td><code>key::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="7">scope</th></tr><tr><td rowspan="3">Attribute Declaration</td><td>Simple Type Definition</td><td><code>scope::<var>qname</var></code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td><code>scope::<var>qname</var></code></td><td>no</td></tr><tr><td>Attribute Group Definition</td><td><code>scope::<var>qname</var></code></td><td>no</td></tr><tr><td rowspan="3">Element Declaration</td><td>Simple Type Definition</td><td><code>scope::<var>qname</var></code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td><code>scope::<var>qname</var></code></td><td>no</td></tr><tr><td>Model Group Definition</td><td><code>scope::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="7">context</th></tr><tr><td rowspan="2">Complex Type Definition</td><td>Element Declaration</td><td><code>context::<var>qname</var></code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td><code>context::<var>qname</var></code></td><td>no</td></tr><tr><td rowspan="4">Simple Type Definition</td><td>Element Declaration</td><td><code>context::<var>qname</var></code></td><td>no</td></tr><tr><td>Attribute Declaration</td><td><code>context::<var>qname</var></code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td><code>context::<var>qname</var></code></td><td>no</td></tr><tr><td>Simple Type Definition</td><td><code>context::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">substitution group affiliation</th></tr><tr><td>Element Declaration</td><td>Element Declaration</td><td><code>substitutionGroup::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="4">term</th></tr><tr><td rowspan="3">Particle</td><td>Element Declaration</td><td><code>schemaElement::<var>qname</var>[<var>n</var>]</code></td><td>yes</td></tr><tr><td>Model Group</td><td><code>model::compositor[<var>n</var>]</code></td><td>yes</td></tr><tr><td>Wildcard</td><td><code>any::*[<var>n</var>]</code></td><td>yes</td></tr></tbody><tbody><tr><th rowspan="7">type definitions</th></tr><tr><td rowspan="2">Attribute Declaration</td><td>Simple Type Definition</td><td><code>type::<var>qname</var></code></td><td>yes</td></tr><tr><td>Complex Type Definition</td><td><code>type::<var>qname</var></code></td><td>yes</td></tr><tr><td rowspan="2">Element Declaration</td><td>Simple Type Definition</td><td><code>type::<var>qname</var></code></td><td>yes</td></tr><tr><td>Complex Type Definition</td><td><code>type::<var>qname</var></code></td><td>yes</td></tr><tr><td rowspan="2">Schema</td><td>Simple Type Definition</td><td><code>type::<var>qname</var></code></td><td>no</td></tr><tr><td>Complex Type Definition</td><td><code>type::<var>qname</var></code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="3">assertions</th></tr><tr><td>Complex Type Definition</td><td>Assertion</td><td><code>assertion::*[<var>n</var>]</code></td><td>no</td></tr><tr><td>Facet</td><td>Assertion</td><td><code>assertion::*[<var>n</var>]</code></td><td>no</td></tr></tbody><tbody><tr><th rowspan="2">alternatives</th></tr><tr><td>Element Declaration</td><td>Type Alternative</td><td><code>alternative::*[<var>n</var>]</code></td><td>no</td></tr></tbody></table></div><div class="div1">
<h2><a id="normative-glossary" name="normative-glossary" />C Glossary (Non-Normative)</h2><p>The listing below is for the benefit of readers of a printed version of this document:
  it collects together all the definitions which appear in the document above.</p><dl><dt><a href="#key-scd">absolute schema component designator</a></dt><dd>An
<b>absolute schema component designator</b> identifies
a particular schema component; it
consists of two parts: a designator
for the assembled schema (a <a title="schema designator" href="#key-sd">schema designator</a>), and a designator for a
particular schema component or schema components relative (a <a title="relative schema component designator" href="#key-relative-scd">relative
schema component designator</a>) to that assembled schema.</dd><dt><a href="#axis-alternatives">alternative-axis</a></dt><dd>The
<b><span><code>alternative</code></span></b> axis
contains
type alternative components linked to the current component
through {alternatives}, {default type definition}, or {type table} arcs,
which are those components
returned by the component-linked() accessor whose component-kind() is
equal to <code><span>xscd:</span>type-alternative</code>.
</dd><dt><a href="#key-ancestor-set">ancestor set</a></dt><dd>The
    <b>ancestor set</b> of the target schema component is the set of schema
    components on the valid canonical path to the current schema component
    together with the current schema component.</dd><dt><a href="#axis-annotation">annotation axis</a></dt><dd>The
<b><span><code>annotation</code></span></b> axis contains annotation
components linked to the current component through {annotation} or
{annotations} arcs, which are the components returned
by the annotations() accessor.
</dd><dt><a href="#axis-anyAttribute">anyAttribute axis</a></dt><dd>The
<b><span><code>anyAttribute</code></span></b> axis contains
wildcard components linked to the current component
through {attribute wildcard} arcs.</dd><dt><a href="#axis-any">any axis</a></dt><dd>The <b><span><code>any</code></span></b>
axis contains
wildcard components linked to the current component
through {wildcard}, {term}, {particle}, {particles}, {content type}, or
{open content} arcs, which is the components returned by the
term() accessor whose component-kind() is equal to
<code><span>xscd:</span>wildcard</code>. </dd><dt><a href="#key-arc">arc</a></dt><dd>A traversal from one component to another
takes place across some particular component property. This property is
the <b>arc</b> of traversal.
</dd><dt><a href="#axis-assertion">assertion axis</a></dt><dd>The
<b><span><code>assertion</code></span></b> axis contains
assertion components linked to the current component
through {assertions}, {value}, or {facets} arcs, which are those components
returned by the assertions() accessor.</dd><dt><a href="#axis-attributeGroup">attributeGroup axis</a></dt><dd>The
<b><span><code>attributeGroup</code></span></b> axis contains
attribute group definition components linked to the current component through
{attribute group definitions} arcs, which are those components
returned by the component-linked() accessor whose component-kind() is equal to
<code><span>xscd:</span>attribute-group-definition</code>.</dd><dt><a href="#axis-attributeUse">attributeUse axis</a></dt><dd>The
<b><span><code>attributeUse</code></span></b> axis contains attribute use components
linked to the current component through {attribute uses}.
</dd><dt><a href="#key-scp-axis">axis</a></dt><dd>A schema component path <b>axis</b>
contains specific components linked to the
current context component through certain kinds of arcs.
Unless otherwise indicated, an axis applied to
a component that has no arc of the required kind designates no components.
</dd><dt><a href="#key-base-attribute-use-set">base attribute use set</a></dt><dd>The <b>base attribute use
set</b> of a schema component is the set consisting of all members of the
{attribute uses} property of members of the base type set of that schema
component.</dd><dt><a href="#key-base-facet-set">base facet set</a></dt><dd>The <b>base facet set</b> of a schema
component is the set consisting of all members of the {facets} property of
members of the base type set of that schema component.</dd><dt><a href="#key-base-particle-set">base particle set</a></dt><dd>The <b>base particle set</b> of a
schema component is the union of all particle sets of all the members of the
extended base type set of that schema component.</dd><dt><a href="#axis-baseType">baseType axis</a></dt><dd>The
<b><span><code>baseType</code></span></b> axis contains
simple type definition and complex type definition components linked to the
current component through {base type definition} arcs.
</dd><dt><a href="#key-base-type-set">base type set</a></dt><dd>
The <b>base type set</b> of a schema component is the set
consisting of the {base type definition} of that schema component and
the {base type definition} of every member of the set.
</dd><dt><a href="#key-canonicalized-xscd">canonicalized xscd XPointer pointer part</a></dt><dd>
A <b><span>canonicalized <code>xscd</code> XPointer pointer part</span></b> is
  an <code>xscd</code> XPointer pointer part whose
  pointer data is a canonical schema
component path.
</dd><dt><a href="#key-canonical-scd">canonical schema component designator</a></dt><dd>
A <b>canonical schema component designator</b>
is an absolute schema component designator that is a URI
that has been mapped from a LEIRI to an IRI in accordance
with the rules given in <a href="#leiri">[LEIRI]</a>, mapped from an IRI to a URI in
accordance with
the rules given in RFC 3987<a href="#rfc3987">[RFC 3987]</a>, and
normalized according to the rules of
syntax-based normalization given there;
and where the relative schema component designator consists of an
<code>xmlns</code> XPointer pointer part (if required) followed
by a <a title="canonicalized xscd XPointer pointer part" href="#key-canonicalized-xscd"><span>canonicalized <code>xscd</code> XPointer pointer part</span></a>.
</dd><dt><a href="#key-canonical-schema-component-path">canonical schema component path</a></dt><dd>The <b>canonical schema
component path</b> of a component is a distinguished valid component path
that uniquely identifies that particular component, that has as few steps as
possible, and that can be deterministically constructed starting from the schema description component, and that contains no
extension axes or accessors.
</dd><dt><a href="#axis-component">component axis</a></dt><dd>The
<b><span><code>component</code></span></b> axis contains the transitive closure of
schema
components that are either linked to the schema description component or that
are linked to current component through default arcs.  That is, it contains
the transitive
closure of the component-children() accessor, as well as
component-linked()
accessor if the schema description is the current component.
</dd><dt><a href="#key-component-relationship">component relationship</a></dt><dd>The
    <b>component relationship</b> is the name of the schema component
    property on the current schema component which references the target schema
    component.
</dd><dt><a href="#axis-context">context axis</a></dt><dd>The
<b><span><code>context</code></span></b> axis contains
complex type definition, attribute declaration, or
element declaration components linked to the current component
through {context} arcs.
</dd><dt><a href="#axis-currentComponent">currentComponent axis</a></dt><dd>The
<b><span><code>currentComponent</code></span></b> axis contains the current component.
</dd><dt><a href="#key-current-component">current schema component</a></dt><dd>The
    <b>current schema component</b> is a schema component for which
    there is a valid canonical path through the schema component graph.</dd><dt><a href="#key-default-arc">default arc</a></dt><dd>A <b>default
arc</b> is a privileged
arc of traversal.
</dd><dt><a href="#axis-elided-component">elided-component axis</a></dt><dd>The
<b><span><code>elided-component</code></span></b> axis contains complex type
definitions
linked to the current component through the {type definition} arc and the
transitive closure of all model group components linked to the current
component. That is, it contains the transitive closure of components returned
from the term() accessor whose component-kind() is equal to
<code><span>xscd:</span>model-group</code>, as well as components linked to the current component
through the {type definition} arc.
</dd><dt><a href="#key-extended-base-type-set">extended base type set</a></dt><dd>The <b>extended base type
set</b> of a schema component is
the set consisting of the {base type definition} of that schema component if
its {derivation} method is "extension" and the {base type definition} of
every member of the set whose {derivation} method is "extension".
</dd><dt><a href="#axis-facet">facet axis</a></dt><dd>The
<b><span><code>facet</code></span></b> axis contains
facet components linked to the current component
through {facets} or {fundamental facets} arcs, which is the components returned
by component-linked() whose component-kind() is equal
to <code><span>xscd:</span>facet</code>.
</dd><dt><a href="#axis-group">group axis</a></dt><dd>The
<b><span><code>group</code></span></b> axis contains
model group definition components linked to the current component through
{model group definitions} arcs, which are those components returned
by the component-linked() accessor whose component-kind() is equal to
<code><span>xscd:</span>model-group-definition</code>.
</dd><dt><a href="#axis-identityConstraint">identityConstraint axis</a></dt><dd>The
<b><span><code>identityConstraint</code></span></b> axis contains
identity constraint definition components linked to the current component
through {identity constraint definitions} arcs, which are those
components returned by the component-linked() accessor whose component-kind()
is equal to <code><span>xscd:</span>identity-constraint-definition</code>.
</dd><dt><a href="#axis-itemType">itemType axis</a></dt><dd>The
<b><span><code>itemType</code></span></b> axis contains
simple type definition components linked to the
current component through {item type definition} arcs.
</dd><dt><a href="#axis-key">key axis</a></dt><dd>The <b><span><code>key</code></span></b>
axis contains
identity constraint definition components linked to the
current component through {referenced key}
arcs.</dd><dt><a href="#axis-memberType">memberType axis</a></dt><dd>The
<b><span><code>memberType</code></span></b> axis contains
simple type definition components linked to the
current component through {member type definitions}
arcs. </dd><dt><a href="#axis-model">model axis</a></dt><dd>The
<b><span><code>model</code></span></b> axis contains
model group components linked to the current component
through {model group}, {term}, {particle}, {particles}, or {content type}
arcs, which are the components returned by the term() accessor
whose component-kind() is equal to <code><span>xscd:</span>model-group</code>.
</dd><dt><a href="#axis-notation">notation axis</a></dt><dd>The
<b><span><code>notation</code></span></b> axis contains
notation declaration components linked to the current component
through {notation declarations}
arcs, which are the components returned by the component-linked() accessor
whose component-kind() is equal to <code><span>xscd:</span>notation-declaration</code>.</dd><dt><a href="#axis-particle">particle axis</a></dt><dd>The
<b><span><code>particle</code></span></b> axis contains particle components
linked to the current component through {particles}.
</dd><dt><a href="#key-particle-set">particle set</a></dt><dd>The <b>particle set</b> of a schema
component is the set consisting
of the {content type} of that schema component with the members of the
{particles} property of the {term} of any member of the set.</dd><dt><a href="#axis-primitiveType">primitiveType axis</a></dt><dd>The
<b><span><code>primitiveType</code></span></b> axis contains
simple type definition components linked to the
current component through {primitive type definition}
arcs.</dd><dt><a href="#key-relative-scd">relative schema component designator</a></dt><dd>A
    <b>relative schema component designator</b>
    identifies a particular schema component relative to
    some current assembled schema; it
    is expressed as an <a href="http://www.w3.org/TR/xptr-framework/#scheme">XPointer scheme</a>
    <code> xscd()</code> that uses a <a title="schema component path" href="#key-scp">schema component path</a>
    as the <a href="http://www.w3.org/TR/xptr-framework/#NT-SchemeData">scheme data</a>.</dd><dt><a href="#key-same-attr-uses">same (attribute uses)</a></dt><dd>Two attribute uses are <b>the
same</b> if the {name} and {target namespace} of their {attribute
declaration} properties are equal. </dd><dt><a href="#key-same-facet">same (facets)</a></dt><dd>Two facets are <b>the same</b> if they
are the same kind of component (e.g. both are length facets) and their {value}
properties have identical values.</dd><dt><a href="#key-same-particle">same (particles)</a></dt><dd>Two particles are <b>the same</b> if
the implementation reports them as the same.</dd><dt><a href="#axis-schemaAttribute">schemaAttribute axis</a></dt><dd>The
<b><span><code>schemaAttribute</code></span></b> axis contains attribute
declaration components linked to the current component through
{attribute declaration} or {attribute declarations} arcs,
which are those components returned by the component-linked() accessor whose
component-kind() is equal to <code><span>xscd:</span>attribute-declaration</code>.
</dd><dt><a href="#key-equal-scd">schema component designators are equal</a></dt><dd>Two
<b>schema component designators are equal</b> if they are absolute
and their URIs are equal or if they are relative to the
same schema, and their <a title="schema component paths are equal" href="#key-equal-path">schema component paths are
equal</a>.</dd><dt><a href="#key-scp-nametest">schema component name test</a></dt><dd>A
<b>schema component name
test</b> is a condition on name of the components selected by the schema
component path step.</dd><dt><a href="#key-scp">schema component path</a></dt><dd>A
<b>schema component path</b> selects a sequence of
schema components in the context of an assembled schema; it is a series
of <a title="step" href="#key-scp-step">steps</a> separated by
'<code>/</code>' or '<code>//</code>'.  Complete schema component paths always
start with either '<code>/</code>' or '<code>//</code>'.
</dd><dt><a href="#key-equal-path">schema component paths are equal</a></dt><dd>Two <b>schema component paths are
equal</b> if they have the same number of
steps, and each step in one path is equal to the corresponding
step in the other. Steps are equal if they have the same
axis, name test (namespace and local name, or wildcard), and predicate.
.</dd><dt><a href="#key-scp-pospred">schema component positional predicate</a></dt><dd>
A <b>schema component positional predicate</b> is a condition on the
relative position of the component in the sequence of matching components from
the schema component path step.</dd><dt><a href="#key-sd">schema designator</a></dt><dd>A <b>schema
designator</b> is a single URI for a resource representing an
assembled schema.</dd><dt><a href="#axis-schemaElement">schemaElement axis</a></dt><dd>The
<b><span><code>schemaElement</code></span></b> axis contains element
declaration components linked to the current component through
{element declarations}, {term}, {particle},
{particles}, or {content type}, which are the components returned by the
term() accessor whose component-kind() is equal to
<code><span>xscd:</span>element-declaration</code>, together with {element declarations}.
</dd><dt><a href="#axis-scope">scope axis</a></dt><dd>The
<b><span><code>scope</code></span></b> axis contains
complex type definition, attribute group definition, or
model group definition components linked to the current component
through {scope} and {parent} arcs, which are the components returned from
the component-scope() accessor.
</dd><dt><a href="#key-scp-step">step</a></dt><dd>A <b>step</b>
consists of a <a title="axis" href="#key-scp-axis">schema component
axis</a> and a <a title="schema component name test" href="#key-scp-nametest">schema component name
test</a> and
an optional <a title="schema component positional predicate" href="#key-scp-pospred">positional predicate</a>.
It selects a sequence of schema components that are linked to a
source component through an arc that matches the axis, pass the name test,
and are selected by the positional predicate, if any.
</dd><dt><a href="#axis-substitutionGroup">substitutionGroup axis</a></dt><dd>The
<b><span><code>substitutionGroup</code></span></b> axis contains
element declaration components linked to the current component
through {substitution group affiliation} and {substitution group affiliations}
arcs.
</dd><dt><a href="#key-target-component">target schema component</a></dt><dd>The
    <b>target schema component</b> is a schema component linked to the
    current schema component via one of the schema component properties
    defined previously.</dd><dt><a href="#axis-type">type axis</a></dt><dd>The <b><span><code>type</code></span></b>
axis contains simple type definition
and complex type definition components linked to the current component through
{type definition}, {type definitions}, {content type},
or {simple type definition} arcs, which are the components
returned by the component-children() accessor whose
component-kind() is equal to either
<code><span>xscd:</span>complex-type-definition</code> or
<code><span>xscd:</span>simple-type-definition</code>.</dd></dl></div><div class="div1">
<h2><a id="references" name="references" />D References</h2><div class="div2">
<h3><a id="N11ED1" name="N11ED1" />D.1 Normative References</h3><dl><dt class="label"><a id="rfc3986" name="rfc3986" />RFC 3986</dt><dd>
<em><a href="http://www.ietf.org/rfc/rfc3986.txt">Uniform Resource
Identifier (URI): Generic Syntax</a></em>, T. Berners-Lee,  R. Fielding,
and L. Masinter.  The Internet Society, January 2005.  This version is
available at
<a href="http://www.ietf.org/rfc/rfc3986.txt">http://www.ietf.org/rfc/rfc3986.txt</a>.
</dd><dt class="label"><a id="xsd2" name="xsd2" />XSD2</dt><dd>
<em><a href="http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/">XML Schema Part 2: Datatypes Second Edition</a></em>,  Paul V. Biron and
Ashok Malhotra, Editors.
World Wide Web Consortium, 28 October 2004. This version is available at
<a href="http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/">http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/</a>.
The latest version is available at
<a href="http://www.w3.org/TR/xmlschema-2/">http://www.w3.org/TR/xmlschema-2/</a>.
</dd><dt class="label"><a id="xptrxmlns" name="xptrxmlns" />XPTR XMLNS</dt><dd>
<em><a href="http://www.w3.org/TR/2003/REC-xptr-xmlns-20030325/">XPointer xmlns() Scheme</a></em>, Steven J. DeRose, Ron Daniel Jr., Eve
Maler, Jonathan Marsh, Editors. World Wide Web Consortium, 25 March 2003.
This version is available at
<a href="http://www.w3.org/TR/2003/REC-xptr-xmlns-20030325/">http://www.w3.org/TR/2003/REC-xptr-xmlns-20030325/</a>.
The latest version is available at
<a href="http://www.w3.org/TR/xptr-xmlns/">http://www.w3.org/TR/xptr-xmlns/</a>.
</dd><dt class="label"><a id="rfc3987" name="rfc3987" />RFC 3987</dt><dd>
<em><a href="http://www.ietf.org/rfc/rfc3987.txt">Internationalized Resource
Identifiers (IRIs)</a></em>, M. Duerst and M. Suignard.  The Internet
Society, January 2005.  This version is available at
<a href="http://www.ietf.org/rfc/rfc3987.txt">http://www.ietf.org/rfc/rfc3987.txt</a>.
</dd><dt class="label"><a id="xsd11_1" name="xsd11_1" />XSD11_1</dt><dd>
<em><a href="http://www.w3.org/TR/2008/WD-xmlschema11-1-20080620/">XML
Schema Definition Language (XSD) 1.1  Part 1: Structures</a></em>, Shundi
Gao, C. M. Sperberg-McQueen, Henry S. Thompson, Editors.
World Wide Web Consortium, 20 June 2008. This
version is available at
<a href="http://www.w3.org/TR/2008/WD-xmlschema11-1-20080620/">http://www.w3.org/TR/2008/WD-xmlschema11-1-20080620/</a>.
The latest version is available at
<a href="http://www.w3.org/TR/xmlschema11-1/">http://www.w3.org/TR/xmlschema11-1/</a>.
</dd><dt class="label"><a id="xptrframework" name="xptrframework" />XPTR</dt><dd>
<em><a href="http://www.w3.org/TR/2003/REC-xptr-framework-20030325/">XPointer
Framework</a></em> Paul Grosso, Eve Maler,
Jonathan Marsh, Norman Walsh, Editors. World Wide Web
Consortium, 25 March 2003.
The current version is available at
<a href="http://www.w3.org/TR/2003/REC-xptr-framework-20030325/">http://www.w3.org/TR/2003/REC-xptr-framework-20030325/</a>
The latest version is available at
<a href="http://www.w3.org/TR/xptr-framework/">http://www.w3.org/TR/xptr-framework/</a>.
</dd><dt class="label"><a id="xsd11_2" name="xsd11_2" />XSD11_2</dt><dd>
<em><a href="http://www.w3.org/TR/2008/WD-xmlschema11-2-20080620/">XML
Schema Definition Language (XSD) 1.1 Part 2: Datatypes</a></em>,
David Peterson, Shundi Gao, Ashok Malhotra, C. M. Sperberg-McQueen, and Henry
S. Thompson, Editors.
World Wide Web Consortium, 20 June 2008. This version is available at
<a href="http://www.w3.org/TR/2008/WD-xmlschema11-2-20080620/">http://www.w3.org/TR/2008/WD-xmlschema11-2-20080620/</a>.
The latest version is available at
<a href="http://www.w3.org/TR/xmlschema11-2/">http://www.w3.org/TR/xmlschema11-2/</a>.
</dd><dt class="label"><a id="xsd1" name="xsd1" />XSD1</dt><dd>
<em><a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/">XML Schema Part 1: Structures (Second
Edition)</a></em>, Henry S. Thompson, David Beech, Murray Maloney and
Noah Mendelsohn, Editors. World Wide Web Consortium, 28 October 2004. This
version is available at
<a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/">http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/</a>.
The latest version is available at
<a href="http://www.w3.org/TR/xmlschema-1/">http://www.w3.org/TR/xmlschema-1/</a>.
</dd><dt class="label"><a id="leiri" name="leiri" />LEIRI</dt><dd>
<em><a href="http://www.w3.org/TR/2008/NOTE-leiri-20081103/">Legacy
extended IRIs for XML resource identification</a></em>, Henry S. Thompson,
Richard Tobin, and Norman Walsh.  World Wide Web Consortium, 3 November 2008.
This version is available at
<a href="http://www.w3.org/TR/2008/NOTE-leiri-20081103/">http://www.w3.org/TR/2008/NOTE-leiri-20081103/</a>.
</dd></dl></div><div class="div2">
<h3><a id="N11FE7" name="N11FE7" />D.2 Non-normative Informational References</h3><dl><dt class="label"><a id="xsd0" name="xsd0" />XSD0</dt><dd>
<em><a href="http://www.w3.org/TR/2004/REC-xmlschema-0-20041028/">XML Schema Part 0: Primer (Second
Edition)</a></em>, David C. Fallside, Editor. World Wide Web Consortium, 28 October 2004. This
version is available at
<a href="http://www.w3.org/TR/2004/REC-xmlschema-0-20041028/">http://www.w3.org/TR/2004/REC-xmlschema-0-20041028/</a>.
The latest version is available at
<a href="http://www.w3.org/TR/xmlschema-0/">http://www.w3.org/TR/xmlschema-0/</a>.
</dd><dt class="label"><a id="dom3" name="dom3" />DOM3</dt><dd>
<em><a href="http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/">
Document Object
Model (DOM) Level 3 Core Specification, Version 1.0</a></em>,
Arnaud Le Hors, et al, Editors. World Wide Web
Consortium, 7 April 2004. This version is available at
<a href="http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/">http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/
</a>.
The latest version is available at
<a href="http://www.w3.org/TR/DOM-Level-3-Core/">http://www.w3.org/TR/DOM-Level-3-Core/
</a>.
</dd></dl></div></div></div></body></html>