The XML Topic Maps (XTM) Syntax 1.1

Table of Contents

1 Introduction
2 Syntax
    2.1 The topicMap element
    2.2 The topic element
    2.3 The subjectIdentity element
    2.4 The baseName element
    2.5 The baseNameString element
    2.6 The variant element
    2.7 The variantName element
    2.8 The parameters element
    2.9 The scope element
    2.10 The instanceOf element
    2.11 The occurrence element
    2.12 The resourceData element
    2.13 The association element
    2.14 The member element
    2.15 The roleSpec element
    2.16 The topicRef element
    2.17 The subjectIndicatorRef element
    2.18 The resourceRef element
    2.19 The mergeMap element
3 Deserialization
    3.1 Common processing rules
        3.1.1 Creating a locator for an element
        3.1.2 Creating locator items
        3.1.3 Creation of new information items
        3.1.4 Processing external references
        3.1.5 Merging topic maps
    3.2 The topicMap element
    3.3 The topic element
    3.4 The subjectIdentity element
    3.5 The baseName element
    3.6 The baseNameString element
    3.7 The variant element
    3.8 The variantName element
    3.9 The parameters element
    3.10 The scope element
    3.11 The instanceOf element
    3.12 The occurrence element
    3.13 The association element
    3.14 The member element
    3.15 The topicRef element
    3.16 The subjectIndicatorRef element
    3.17 The resourceRef element
    3.18 The mergeMap element
4 Conformance

Appendices

A References
B The XTM 1.1 DTD
C A RELAX-NG schema for XTM 1.1 (Non-Normative)
D A XML Schema schema for XTM 1.1 (Non-Normative)
E Serialization (Non-Normative)
F Differences with XTM 1.0 (Non-Normative)
G Resolved issues (Non-Normative)

1 Introduction

XTM 1.1 is a syntax for the interchange of topic maps. The syntax is not designed to be extended or modified, although topic maps expressed in XTM may be embedded in other XML syntaxes. Other XML syntaxes that represent topic map information may well define mappings to the XTM syntax, however. Ease of human XTM authoring was not prioritized during the design of the syntax, and consequently it is not recommended to edit the syntax directly.

An XTM topic map is a topic map serialized in XTM syntax as a topicMap element with descendants. An XTM document is an XML document that contains one or more XTM topic maps. In a process known as deserialization, the XTM topic map is read by a topic map processor, which produces from it some representation of the Standard Application Model, by following a procedure equivalent to the one defined in 3 Deserialization. Note that if the same document contains multiple topicMap elements the result will be a separate SAM instance for each element.

The deserialization procedure is defined as a transformation that takes an element item from an XML Information Set [infoset] as input and produces a Standard Application Model instance as output. This specification does not concern itself with the means by which the XML Information Set used as input is produced. In most cases it will be produced by parsing an XML document, but other possibilities are specifically allowed, including architectural processing (as defined in [HyTime]) or XSLT transformations from other XML syntaxes.

This specification also provides informative guidance on how to serialize instances of the Standard Application Model to the XTM syntax.

Issue (xtm-namespace-uri):

Should the version number in the XTM namespace URI be changed?

2 Syntax

This section defines the XTM syntax, using prose and a DTD. The full DTD can be found in B The XTM 1.1 DTD.

2.1 The topicMap element

The topicMap element is the root element of all XTM topic maps. It acts as a container for the topic map, and can be either the document element of an XML document, or it may be the root of a subtree inside an XML document that contains more than just a single topic map. In both cases, the input to the XTM deserialization process is the subtree contained by the topicMap element.

The topicMap element type is declared as follows:

<!ELEMENT topicMap

   ( topic | association | mergeMap )*

>

<!ATTLIST topicMap

     id              ID        #IMPLIED

     xmlns           CDATA     #FIXED 'http://www.topicmaps.org/xtm/1.0/'

     xmlns:xlink     CDATA     #FIXED 'http://www.w3.org/1999/xlink'

     xml:base        CDATA     #IMPLIED

>

The attributes have the following meanings:

id

A unique identifier for the topic map within the document. Used to refer to the topic map.

xml:base

An attribute used to override the base URI of the document inside the topicMap element, as specified in [XMLBase].

xmlns

This attribute declares the default namespace and sets it to the XTM namespace URI.

Issue (xtm-fixed-attributes):

Attributes declared as #FIXED in the DTD can not be guaranteed to always be present in the XML document as parsed, either because there is no DOCTYPE declaration, or because the parser does not read the DTD. This affects both namespace and XLink parsing, which again affects the procedure used to recognize element types.

xmlns:xlink

This attribute declares the xlink namespace prefix and sets it to the XLink namespace URI [XLink].

Issue (xtm-topicmap-version):

Should the topicMap element have a version attribute?

2.2 The topic element

The topic element type is used to create topics, and acts as a container and point of reference for topic information. The child elements of the topic element provide some topic characteristic assignments, as well as other properties, while association roles played by the topic are specified outside the topic element.

The topic element type is declared as follows:

<!ELEMENT topic 

   ( instanceOf*, subjectIdentity?, ( baseName | occurrence )* )

>

<!ATTLIST topic

   id              ID        #REQUIRED

>

The id attribute provides a unique identifier for the topic, which is used to refer to it.

2.3 The subjectIdentity element

The subjectIdentity element type may in its child elemets contain formal declarations of the subject of the topic defined by the parent element.

The subjectIdentity element type is declared as follows:

<!ELEMENT subjectIdentity

   ( topicRef | resourceRef| subjectIndicatorRef )*

>

<!ATTLIST subjectIdentity

   id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.4 The baseName element

The baseName element type is used to add topic names to the topic created by the parent topic element. The child elements of the baseName element provide the property values of the topic name item.

The baseName element type is declared as follows:

<!ELEMENT baseName

   ( instanceOf?, scope?, baseNameString, variant* )

>

<!ATTLIST baseName

   id              ID        #IMPLIED

>

The id attribute provides a unique identifier for the topic name, which can be used to refer to it.

2.5 The baseNameString element

The baseNameString element type is used to provide the string that makes up a base name.

The baseNameString element type is declared as follows:

<!ELEMENT baseNameString  ( #PCDATA ) >

<!ATTLIST baseNameString

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.6 The variant element

The variant element type is used to create a variant name of a base name, and may also contain other variant names with scopes that are supersets of the scope of that of the containing variant name.

The variant element type is declared as follows:

<!ELEMENT variant

   ( parameters, variantName?, variant* )

>

<!ATTLIST variant

     id              ID        #IMPLIED

>

The id attribute provides a unique identifier for the variant name, which is used to refer to it.

2.7 The variantName element

The variantName element type is used to contain the element that specifies the information resource that is the actual variant name.

The variantName element type is declared as follows:

<!ELEMENT variantName

   ( resourceRef | resourceData )

>

<!ATTLIST variantName

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.8 The parameters element

The parameters element type is used to specify the scope of a variant name, in addition to the scope it inherits from its parent topic name or variant name.

The parameters element type is declared as follows:

<!ELEMENT parameters

   ( topicRef | resourceRef | subjectIndicatorRef )+

>

<!ATTLIST parameters

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.9 The scope element

The scope element type is used throughout XTM to indicate the scope of a topic characteristic assignment.

The scope element type is declared as follows:

<!ELEMENT scope

   ( topicRef | resourceRef | subjectIndicatorRef )+

>

<!ATTLIST scope

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.10 The instanceOf element

The instanceOf element type is used throughout XTM to indicate the type of the construct represented by its parent element. The type is always a topic, indicated by the child element.

The instanceOf element type is declared as follows:

<!ELEMENT instanceOf

   ( topicRef | resourceRef | subjectIndicatorRef )

>

<!ATTLIST instanceOf

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.11 The occurrence element

The occurrence element type is used to assign an occurrence to a the topic defined by the parent element.

The occurrence element type is declared as follows:

<!ELEMENT occurrence

   ( instanceOf?, scope?, ( resourceRef | resourceData ) )

>

<!ATTLIST occurrence

     id              ID        #IMPLIED

>

The id attribute is used to refer to the occurrence.

2.12 The resourceData element

The resourceData element type is used to provide an information resource in the form of a string contained within the XTM document. This information resource may be either a variant name or an occurrence.

The resourceData element type is declared as follows:

<!ELEMENT resourceData

   ( #PCDATA )

>

<!ATTLIST resourceData

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

Issue (xtm-resourcedata-markup):

Should we extend the content model of resourceData to allow arbitrary markup within the element, and require implementations to be able to represent this?

2.13 The association element

The association element type is used to express associations between topics. The member child elements provide the association role players of the association.

The association element type is declared as follows:

<!ELEMENT association

   ( instanceOf?, scope?, member+ )

>

<!ATTLIST association

     id              ID        #IMPLIED

>

The id attribute is used to refer to the association.

2.14 The member element

The member element type is used to add one or more players of the same association role type to the association created by the association parent element.

The member element type is declared as follows:

<!ELEMENT member

   ( roleSpec?, ( topicRef | resourceRef | subjectIndicatorRef )* )

>

<!ATTLIST member

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

Issue (xtm-member-id):

Should the id attribute of member be ignored? This makes it impossible to reify association roles in XTM. On the other hand, member elements do not necessarily map to a single association role item.

2.15 The roleSpec element

The roleSpec element type is used to specify the association role type played by the association player contained in the member parent element.

The roleSpec element type is declared as follows:

<!ELEMENT roleSpec

   ( topicRef | resourceRef | subjectIndicatorRef )

>

<!ATTLIST roleSpec

     id              ID        #IMPLIED

>

The id attribute is ignored during deserialization.

2.16 The topicRef element

The topicRef element type is used throughout XTM to refer to a topic, either within the same XML document or externally. The signficance of the reference depends on the context.

The topicRef element type is declared as follows:

<!ELEMENT topicRef EMPTY>

<!ATTLIST topicRef

     id              ID        #IMPLIED

     xlink:href      CDATA     #REQUIRED

     xlink:type      NMTOKEN   #FIXED 'simple'

>

The attributes have the following meanings:

id

This attribute is ignored during deserialization.

xlink:href

Contains the URI that is the topic reference. This URI must have a fragment identifier and must be what [XPointer] calls a shorthand pointer (formerly barename).

Issue (xtm-topicref-notatopic):

Is it an error for a topicRef element to refer to an element that is not a topic element?

Issue (xtm-topicref-xtmwrap):

What if the topicRef element refers to a topic in an external resource where the topicMap element is not the document element. Is that an error? What if there is more than one topicMap element?

2.17 The subjectIndicatorRef element

The subjectIndicatorRef element type is used throughout XTM to refer to a subject indicator. The signficance of the reference depends on the context.

The subjectIndicatorRef element type is declared as follows:

<!ELEMENT subjectIndicatorRef EMPTY>

<!ATTLIST subjectIndicatorRef

     id              ID        #IMPLIED

     xlink:href      CDATA     #REQUIRED

     xlink:type      NMTOKEN   #FIXED 'simple'

>

The attributes have the following meanings:

id

This attribute is ignored during deserialization.

xlink:href

Contains the URI of the subject indicator being referred to.

2.18 The resourceRef element

The resourceRef element type is used throughout XTM to refer to an information resource. The signficance of the reference depends on the context.

The resourceRef element type is declared as follows:

<!ELEMENT resourceRef EMPTY>

<!ATTLIST resourceRef

     id              ID        #IMPLIED

     xlink:href      CDATA     #REQUIRED

     xlink:type      NMTOKEN   #FIXED 'simple'

>

The attributes have the following meanings:

id

This attribute is ignored during deserialization.

xlink:href

Contains the URI of the information resource being referred to.

2.19 The mergeMap element

The mergeMap element type is used throughout XTM to refer to external topic maps that are to be merged into the topic map that contains the mergeMap element. The child elements of the mergeMap element specify topics to be added to the scopes of all topic characteristic assignments in the topic map to be merged in.

The mergeMap element type is declared as follows:

<!ELEMENT mergeMap

     ( topicRef | resourceRef | subjectIndicatorRef )*

>

<!ATTLIST mergeMap

     id              ID        #IMPLIED

     xlink:type      NMTOKEN   #FIXED 'simple'

     xlink:href      CDATA     #REQUIRED

>

The attributes have the following meanings:

id

This attribute is ignored during deserialization.

xlink:type

This attribute declares the mergeMap element to be a simple XLink element.

xlink:href

This attribute contains the URI that refers to the topic map to be merged into the current topic map. It must refer either to a topicMap element, or to an XTM document. If it has a fragment identifier that identifier must be what [XPointer] calls a shorthand pointer (formerly barename).

Issue (xtm-mergemap-reference):

Is it an error if a mergeMap element refers to an XML document that contains multiple topicMap elements without providing a disambiguating fragment reference?

3 Deserialization

This section defines how instances of the XTM syntax are deserialized into instances of the Standard Application Model [SAM].

The input to the deserialization process is:

·         An element item as defined by [infoset], representing a topicMap element. In most cases this will be the document element, but in cases where the topicMap element is embedded in other XML syntaxes applications may select one element item and use it as the input to the deserialization process. The means by which this element item is chosen are beyond the scope of this specification. It is an error if this element item is not valid according to the DTD given in B The XTM 1.1 DTD.

·         An absolute URI. This is the URI from which the XML document was retrieved, known as the document URI. This URI must always be provided, as it is necessary in order to assign the source locators of the information items created during deserialization. If the XML document was not read from any particular URI the application is responsible for providing a URI it considers suitable.

Deserialization is done by processing each element item in the input subtree of the XML Information Set in document order. For each element item encountered the operations specified in the subsection labelled "Processing" inside the section about that element type are performed.

An input element item matches a section in this document when the [namespace name] property is set to "http://www.topicmaps.org/xtm/1.0/", and the [local name] matches the element type name given in that section. Elements that do not match any section are ignored.

Note:

The definition of the string type in SAM requires that all strings created during deserialization be represented using Unicode Normalization Form C. This means that processors are required to apply normalization before making strings available to the application.

Issue (xtm-namespace-support):

The text as specified here requires that XTM processors do XML Namespace processing. Is that acceptable? XTM 1.0 seems to imply that namespace processing is optional. Also, proper namespace processing allows the use of different namespace prefixes, which break straight DTD validation.

Issue (xtm-unknown-elements):

Unknown elements are ignored in order to ensure forwards compatibility, but this means DTD compliance cannot be required. Which is more important?

3.1 Common processing rules

This section defines common processing rules used throughout this specification. These rules are referenced from the sections they apply to.

3.1.1 Creating a locator for an element

The URI of an element is computed by first concatenating the "#" character and the value of the [normalized value] property of the attribute item in the [attributes] property of that element item whose [local name] property is set to "id". This yields a relative URI that is then resolved to an absolute URI by using the URI found in the [base URI] property of the element item as the base URI.

Issue (xtm-same-doc-refs):

RFC 2396, section 4.2, specifies that URI references of the form "" and "#fragment" are resolved relative to the URI of the current entity. Should XTM should follow this?

Finally, a locator item is created, with its [notation] property set to "URI" and the URI in its [reference] property.

3.1.2 Creating locator items

Creation of a locator item from an element information item in the XML Infoset is done by:

·         locating the attribute information item in the element's [attributes] property whose [namespace name] property is set to the XLink namespace URI and whose [local name] property is set to "href",

·         the value of the attribute information item's [normalized value] property is unescaped by replacing %HH escape sequences with the characters they represent, and the resulting character sequence is decoded from UTF-8 to a sequence of abstract Unicode characters,

·         the resulting string is turned into an absolute URI by resolving it against the URI in the [base URI] property of the element information item, and

·         finally a locator item is created with its [notation] property set to "URI" and its [reference] property set to the URI produced by the previous step.

Ed. Note:
Dependency on the xtm-same-doc-refs issue here.

3.1.3 Creation of new information items

Whenever a new information item is created, those of its properties which have set values are set to the empty set, while the other properties are initialized to null.

3.1.4 Processing external references

The URI to the external information resource is resolved and the result is parsed with an XML parser according to [XML] to produce an XML Information Set according to [infoset]. It is an error if the information resource cannot be retrieved or if the result is not a well-formed XML document.

Note:

Unfortunately, the parsing of XML documents may yield different XML Information Sets depending on whether a validating or a non-validating XML parser is used and also on which parser is used, even if the parser is fully conformant. For interoperability it is recommended not to use XML features that different XML parsers may interpret differently.

The XML Information Set is then traversed to find element items that match section 3.2 The topicMap element and for each element item found a SAM instance is built using the procedure in 3 Deserialization with the element item and the URI of the information resource as input. The SAM instances are then returned as the result of processing.

3.1.5 Merging topic maps

A topic map item B loaded from an external reference can be merged into another topic map item A currently being deserialized by:

·         Adding all topic items in B's [topics] property to A's [topics] property.

·         Adding all association items in B's [associations] property to A's [associations] property.

Ed. Note:
This punts on typing, scoping, and role playing topics.

3.2 The topicMap element

The topicMap element causes a topic map item to be created.

If the topicMap element has an id attribute a locator item is created, as defined in 3.1.1 Creating a locator for an element, and added to the [source locators] property of the topic map item.

If the topicMap element has an xml:base attribute this does not affect the Standard Application Model instance being built, except insofar as it modifies the input XML Information Set.

3.3 The topic element

The topic element causes a topic item to be created and inserted into the [topics] property of the topic map item.

The id attribute causes a locator item to be created, as defined in 3.1.1 Creating a locator for an element, and added to the [source locators] property of the topic item.

3.4 The subjectIdentity element

The subjectIdentity element has no direct effect on the information set, but changes the interpretation of the child elements. The child elements are processed as follows:

·         If there is a resourceRef child, a locator item is produced according to the procedure described in 3.1.2 Creating locator items. That locator item is then added to the [subject addresses] property of the topic item created by the parent topic element.

·         For every subjectIndicatorRef child, a locator item is produced according to the procedure described in 3.1.2 Creating locator items. That locator item is then added to the [subject identifiers] property of the topic item created by the parent topic element.

·         For every topicRef child a topic item is produced according to the rules of 3.15 The topicRef element. That topic item is then merged with the topic item created from the parent topic element according to the rules of the Standard Application Model, 4.1 Merging topics.

If the subjectIdentity element has an id attribute that attribute is ignored.

3.5 The baseName element

The baseName element causes a base name item to be created, and added to the [base names] property of the topic item created by the parent topic element.

If the baseName element has an id attribute a locator item is created, as defined in 3.1.1 Creating a locator for an element, and added to the [source locators] property of the base name item.

3.6 The baseNameString element

The information items in the [children] property of the baseNameString element are traversed, and for each character information item the Unicode character specified by the [character code] property is added to the [value] property of the base name item created by the parent baseName element.

If the baseNameString element has an id attribute that attribute is ignored.

3.7 The variant element

The variant element causes a variant item to be created and added to the [variants] property of the base name item created by its baseName ancestor.

If the variant element has an id attribute a locator item is created, as defined in 3.1.1 Creating a locator for an element, and added to the [source locators] property of the variant item.

The [scope] property is initialized to the value of the [scope] property of the variant or base name item created by the parent element (which will be either a baseName element or a variant element).

Note:

It is here assumed that the scope of the parent element has already been processed, which it will have been, so long as the document is valid.

3.8 The variantName element

The variantName element has no direct effect on the information set being produced, but changes the interpretation of its child element. The child element is processed as follows:

·         If the child element is a resourceRef element a locator item is produced from it following the procedure in 3.1.2 Creating locator items. This locator item is set as the value of the [resource] property of the new variant item.

·         If the child element is a resourceData element the information items in the [children] property of the element item are traversed, and for each character information item the Unicode character specified by the [character code] property is added to the [value] property of the variant item created by the parent variant element.

If the variantName element has an id attribute that attribute is ignored.

3.9 The parameters element

The parameters element has no direct effect on the information set being produced, but changes the interpretation of its child elements. Each topicRef, resourceRef, and subjectIndicatorRef child element is processed according to the rules for that element type to produce a topic item. These topic items are gathered into a set that is assigned as the value of the [scope] property of the variant item produced by the parent element.

If the parameters element has an id attribute that attribute is ignored.

3.10 The scope element

The scope element has no direct effect on the information set being produced, but changes the interpretation of its child elements. Each topicRef, resourceRef, and subjectIndicatorRef child element is processed according to the rules for that element type to produce a topic item. These topic items are gathered into a set that is assigned as the value of the [scope] property of the information item produced by the parent element.

If the scope element has an id attribute that attribute is ignored.

3.11 The instanceOf element

The instanceOf element has no direct effect on the information set being produced, but changes the interpretation of its child elements. The exact interpretation depends on the parent element of the instanceOf element, however.

Regardless of what parent element the instanceOf element is found in, the child element produces a topic item. If it is a topicRef element the procedure in 3.15 The topicRef element is followed; if it is a resourceRef element the procedure in 3.17 The resourceRef element is followed; if it is a subjectIndicatorRef element the procedure in 3.16 The subjectIndicatorRef element is followed.

If the parent element is a baseName, occurrence, or association element, the produced topic item is set as the value of the [type] property of the information item produced by the parent element.

If the parent element is a topic element a new association item is created, with two association role items in its [association roles] property. The topic item representing the type-instance association type (described in The Standard Application Model, 5.1 The type-instance relationship) is set as the value of its [type] property.

The first association role item has its [type] property set to the topic item representing the class role in the same association (see the section referenced above), while the [role playing topic] property is set to the topic produced by the child element.

The second association role item has its [type] property set to the topic item representing the instance role in the same association (see the section referenced above), while the [role playing topic] property is set to the topic produced by the parent element (that is, the current topic).

If the instanceOf element has an id attribute that attribute is ignored.

3.12 The occurrence element

The occurrence element causes an occurrence item to be created, and added to the [occurrences] property of the topic item created by the parent topic element.

If the occurrence element has an id attribute a locator item is created, as defined in 3.1.1 Creating a locator for an element, added to the [source locators] property of the occurrence item.

If the occurrence element has a resourceData child element the information items in the [children] property of that element item are traversed, and for each character information item the Unicode character specified by the [character code] property is added to the [value] property of the occurrence item created by the parent occurrence element.

If the occurrence element has a resourceRef child element a locator item is produced from it according to the rules of 3.1.2 Creating locator items. This locator is set as the value of the [resource] property of the new occurrence item.

3.13 The association element

The association element causes an association item to be created, and added to the [association] property of the topic map item.

If the association element has an id attribute a locator item is created, as defined in 3.1.1 Creating a locator for an element, and added to the [source locators] property of the association item.

3.14 The member element

The member element does not have any direct impact on the information set being created, but affects the processing of its descendant elements.

For each topicRef, resourceRef, and subjectIndicatorRef child of the member element a topic item is produced according to the rules for its element type. An association role item is created, and this topic item is then set as the value of its [role playing topic] property. The association role item is then added to the [association roles] property of the association item.

If the member element has no topicRef, subjectIndicatorRef, or resourceRef children a new association role item is created anyway. A new topic item is created and set as the value of its [role playing topic] property, and the association role item is then added to the [association roles] property of the association item.

If the member element has a roleSpec child element, which again has a topicRef, resourceRef, or subjectIndicatorRef child element, a topic item is produced according to the rules for its element type. That topic item is then set as the value of the [type] property of each association role item produced above.

If the member element no roleSpec child element a new topic item is created and set as the value of the [type] property of each association role item produced above.

If the member element has an id attribute its value is ignored.

3.15 The topicRef element

The topicRef element always produces a topic item, as described below. How the topic item is used depends on the context in which the topicRef element appears, and is described in the part of this document describing the processing of the topicRef element's parent element.

From the topicRef element a locator item is produced according to the rules in 3.1.2 Creating locator items. If the topic map processor has not already processed the information resource referred to by the URI (as identified by the part of the URI before the fragment identifier) that information resource is processed using this URI (as described in 3.1.4 Processing external references) to find a set of SAM model instances. It is an error if there is not exactly one SAM model instance. That SAM model instance is then merged with the one being built following the procedure in 3.1.5 Merging topic maps.

If the information set has a topic item whose [subject identifiers] or [source locators] properties contain a locator item equal to the one produced above that topic item is the one produced by this topicRef element.

If no such topic item exists, a topic item is created, and the locator item added to its [source locators] property. That topic item is then the one produced by this topicRef element.

If the topicRef element has an id attribute that attribute is ignored.

3.16 The subjectIndicatorRef element

The subjectIndicatorRef element produces a topic item, as described below. How the topic item is used depends on the context in which the subjectIndicatorRef element appears, and is described in the part of this document describing the processing of the subjectIndicatorRef element's parent element.

From the subjectIndicatorRef element a locator item is produced according to the rules in 3.1.2 Creating locator items. If the information set has a topic item whose [subject identifiers] or [source locators] properties contain a locator item equal to the one produced above that topic item is the one produced by this subjectIndicatorRef element.

If no such topic item exists, a topic item is created, and the locator item added to its [subject identifiers] property. That topic item is then the one produced by this subjectIndicatorRef element.

If the subjectIndicatorRef element has an id attribute that attribute is ignored.

3.17 The resourceRef element

The resourceRef element produces a topic item, as described below. How the topic item is used depends on the context in which the resourceRef element appears, and is described in the part of this document describing the processing of the resourceRef element's parent element.

From the resourceRef element a locator item is produced with according to the rules in 3.1.2 Creating locator items. If the information set has a topic item whose [subject addresses] property contains a locator item equal to the one produced above that topic item is the one produced by this resourceRef element.

If no such topic item exists, a topic item is created, and the locator item add to its [subject addresses] property. That topic item is then the one produced by this resourceRef element.

If the resourceRef element has an id attribute that attribute is ignored.

3.18 The mergeMap element

An absolute URI is produced from the mergeMap element's xlink:href attribute, following the procedure in 3.1.2 Creating locator items. If the information resource referred to by that URI has already been processed nothing further is done. If it has not a set of SAM instances is produced as described in 3.1.4 Processing external references. After this there are two possibilities:

·         If the URI has a fragment identifier the SAM instance whose topic map item has the corresponding locator item in its [source locators] property is chosen. It is an error if there is no such SAM instance.

·         If the URI has no fragment identifier it is an error if the set of SAM instances does not have a single member. That member is then chosen.

For each topicRef, resourceRef, and subjectIndicatorRef child element of the mergeMap element a topic item produced is produced as described in the section for that element type and added to the [scope] property of every information item in the SAM instance produced above. Finally, the SAM instance is merged into the current SAM instance, following the procedure described in 3.1.5 Merging topic maps.

If the mergeMap element has an id attribute that attribute is ignored, as is the value of its xlink:type attribute.

Issue (xtm-mergemap-and-topicref):

What is the correct behaviour if a topicRef to an external document occurs first, followed by a mergeMap with added themes?

4 Conformance

A topic map processor conforms to this specification provided that it meets all the requirements given below.

·         The topic map processor must reject information resources which are not well-formed XML from deserialization, as well as XML documents where the topicMap elements and descendants do not conform to the XTM 1.1 DTD.

·         The topic map processor must reject all XTM topic maps which cause SAM constraints to be violated during deserialization.

·         The topic map processor must detect all errors defined in this Technical Specification and reject all XTM topic maps which have such errors.

·         For all XTM topic maps which are not rejected the topic map processor must build a representation that is isomorphic to the SAM instance created by the procedure given in 3 Deserialization.

A References

HyTime

ISO 10744:1997, Information processing — Text and office systems — Hypermedia/Time-based Structuring Language (HyTime).

infoset

XML Information Set, J. Cowan and R. Tobin, editors. World Wide Web Consortium. 24 October 2001.

SAM

The Standard Application Model for Topic Maps, G. Moore and L. M. Garshol (authors), ISO SC34/WG3.

tm-guide

Guide to the topic map standardization process, Lars Marius Garshol, 2002-06-23, ISO/IEC JTC1 SC34/N0323.

XML

Extensible Markup Language (XML) 1.0 (Second Edition), T. Bray, J. Paoli, C.M. Sperberg-McQueen, and E. Maler, editors. World Wide Web Consortium, W3C Recommendation 6 October 2000.

XMLBase

XML Base, World Wide Web Consortium. February 2000. J. Marsh, editor.

XLink

XML Linking Language (XLink) Version 1.0, World Wide Web Consortium. 27 June 2001. S. DeRose, E. Maler, and D. Orchard, editors.

XPointer

XPointer Framework, World Wide Web Consortium. 25 March 2003. P. Grosso, E. Maler, J. Marsh, N. Walsh, editors.

XTM1.0

XML Topic Maps (XTM) 1.0 Specification, TopicMaps.Org, 2001.

B The XTM 1.1 DTD

<!-- ....................................................................... -->

<!-- XML Topic Map DTD  .................................................... -->

<!-- XML Topic Map (XTM) DTD, Version 1.1

     This is XTM, an XML interchange syntax for ISO 13250 Topic Maps.

     Use this URI to identify the default XTM namespace:

         "http://www.topicMaps.org/xtm/1.0/"

     Used to identify the XLink namespace:

         "http://www.w3.org/1999/xlink"

-->

<!-- topicMap: Topic Map document element ........................ -->

<!ELEMENT topicMap

   ( topic | association | mergeMap )*

>

<!ATTLIST topicMap

   id              ID        #IMPLIED

   xmlns           CDATA     #FIXED 'http://www.topicmaps.org/xtm/1.0/'

   xmlns:xlink     CDATA     #FIXED 'http://www.w3.org/1999/xlink'

   xml:base        CDATA     #IMPLIED

>

<!-- topic: Topic element ....................................... -->

<!ELEMENT topic

   ( instanceOf*, subjectIdentity?, ( baseName | occurrence )* )

>

<!ATTLIST topic

   id              ID        #REQUIRED

>

<!-- instanceOf: Points to a Topic representing a class .......... -->

<!ELEMENT instanceOf  ( topicRef | resourceRef | subjectIndicatorRef ) >

<!ATTLIST instanceOf

   id              ID        #IMPLIED

>

<!-- subjectIdentity: Subject reified by Topic ................... -->

<!ELEMENT subjectIdentity

   ( topicRef | resourceRef | subjectIndicatorRef )*

>

<!ATTLIST subjectIdentity

   id              ID        #IMPLIED

>

<!-- topicRef: Reference to a Topic element ...................... -->

<!ELEMENT topicRef  EMPTY >

<!ATTLIST topicRef

   id              ID        #IMPLIED

   xlink:type      NMTOKEN   #FIXED 'simple'

   xlink:href      CDATA     #REQUIRED

>

<!-- subjectIndicatorRef: Reference to a Subject Indicator ....... -->

<!ELEMENT subjectIndicatorRef  EMPTY >

<!ATTLIST subjectIndicatorRef

   id              ID        #IMPLIED

   xlink:type      NMTOKEN   #FIXED 'simple'

   xlink:href      CDATA     #REQUIRED

>

<!-- baseName: Base Name of a Topic .............................. -->

<!ELEMENT baseName  ( instanceOf?, scope?, baseNameString, variant* ) >

<!ATTLIST baseName

   id              ID        #IMPLIED

>

<!-- baseNameString: Base Name String container .................. -->

<!ELEMENT baseNameString  ( #PCDATA ) >

<!ATTLIST baseNameString

   id              ID        #IMPLIED

>

<!-- variant: Alternate forms of Base Name ....................... -->

<!ELEMENT variant  ( parameters, variantName?, variant* ) >

<!ATTLIST variant

   id              ID        #IMPLIED

>

<!-- variantName: Container for Variant Name ..................... -->

<!ELEMENT variantName  ( resourceRef | resourceData ) >

<!ATTLIST variantName

   id              ID        #IMPLIED

>

<!-- parameters: Processing context for Variant .................. -->

<!ELEMENT parameters  ( topicRef | resourceRef | subjectIndicatorRef )+ >

<!ATTLIST parameters

   id              ID        #IMPLIED

>

<!-- occurrence: Resources regarded as an Occurrence ............. -->

<!ELEMENT occurrence

   ( instanceOf?, scope?, ( resourceRef | resourceData ) )

>

<!ATTLIST occurrence

   id              ID        #IMPLIED

>

<!-- resourceRef: Reference to a Resource ........................ -->

<!ELEMENT resourceRef  EMPTY >

<!ATTLIST resourceRef

   id              ID        #IMPLIED

   xlink:type      NMTOKEN   #FIXED 'simple'

   xlink:href      CDATA     #REQUIRED

>

<!-- resourceData: Container for Resource Data ................... -->

<!ELEMENT resourceData  ( #PCDATA ) >

<!ATTLIST resourceData

   id              ID        #IMPLIED

>

<!-- association: Topic Association  ............................. -->

<!ELEMENT association

   ( instanceOf?, scope?, member+ )

>

<!ATTLIST association

   id              ID        #IMPLIED

>

<!-- member: Member in Topic Association ......................... -->

<!ELEMENT member

   ( roleSpec?, ( topicRef | resourceRef | subjectIndicatorRef )* )

>

<!ATTLIST member

   id              ID        #IMPLIED

>

<!-- roleSpec: Points to a Topic serving as an Association Role .. -->

<!ELEMENT roleSpec  ( topicRef | resourceRef | subjectIndicatorRef ) >

<!ATTLIST roleSpec

   id              ID        #IMPLIED

>

<!-- scope: Reference to Topic(s) that comprise the Scope ........ -->

<!ELEMENT scope  ( topicRef  | resourceRef | subjectIndicatorRef )+ >

<!ATTLIST scope

   id              ID        #IMPLIED

>

<!-- mergeMap: Merge with another Topic Map ...................... -->

<!ELEMENT mergeMap  ( topicRef | resourceRef | subjectIndicatorRef )* >

<!ATTLIST mergeMap

   id              ID        #IMPLIED

   xlink:type      NMTOKEN   #FIXED 'simple'

   xlink:href      CDATA     #REQUIRED

>

<!-- end of XML Topic Map (XTM) 1.1 DTD -->

C A RELAX-NG schema for XTM 1.1 (Non-Normative)

<?xml version="1.0" encoding="UTF-8"?>

<!-- ............................................................. -->

<!-- XML Topic Maps 1.1  ......................................... -->

<!-- XML Topic Map (XTM) 1.1

     This is an informative RELAX-NG schema for the XTM 1.1 syntax, to

     be published as part of ISO 13250.

-->

<!-- ............................................................. -->

<grammar xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0" 

         xmlns:xlink="http://www.w3.org/1999/xlink" 

         ns="http://www.topicmaps.org/xtm/1.0/" 

         xmlns="http://relaxng.org/ns/structure/1.0" 

         datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">

  <!-- topicMap: Topic Map document element ........................ -->

  <define name="topicMap">

    <element name="topicMap">

      <ref name="attlist.topicMap"/>

      <zeroOrMore>

        <choice>

          <ref name="topic"/>

          <ref name="association"/>

          <ref name="mergeMap"/>

        </choice>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.topicMap" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

    <optional>

      <attribute name="xml:base">

        <data type="anyURI"/>

      </attribute>

    </optional>

  </define>

  <!-- topic: Topic element ........................................ -->

  <define name="topic">

    <element name="topic">

      <ref name="attlist.topic"/>

      <zeroOrMore>

        <ref name="instanceOf"/>

      </zeroOrMore>

      <optional>

        <ref name="subjectIdentity"/>

      </optional>

      <zeroOrMore>

        <choice>

          <ref name="baseName"/>

          <ref name="occurrence"/>

        </choice>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.topic" combine="interleave">

    <attribute name="id">

      <data type="ID"/>

    </attribute>

  </define>

  <!-- instanceOf: Points To a Topic representing a class .......... -->

  <define name="instanceOf">

    <element name="instanceOf">

      <ref name="attlist.instanceOf"/>

      <choice>

        <ref name="topicRef"/>

        <ref name="resourceRef"/>

        <ref name="subjectIndicatorRef"/>

      </choice>

    </element>

  </define>

  <define name="attlist.instanceOf" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- subjectIdentity: Subject reified by Topic ................... -->

  <define name="subjectIdentity">

    <element name="subjectIdentity">

      <ref name="attlist.subjectIdentity"/>

      <zeroOrMore>

        <choice>

          <ref name="topicRef"/>

          <ref name="resourceRef"/>

          <ref name="subjectIndicatorRef"/>

        </choice>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.subjectIdentity" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- topicRef: Reference to a Topic element ...................... -->

  <define name="topicRef">

    <element name="topicRef">

      <ref name="attlist.topicRef"/>

      <empty/>

    </element>

  </define>

  <define name="attlist.topicRef" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

    <optional>

      <attribute name="xlink:type" a:defaultValue="simple">

        <value type="NMTOKEN">simple</value>

      </attribute>

    </optional>

    <attribute name="xlink:href">

      <data type="anyURI"/>

    </attribute>

  </define>

  <!-- subjectIndicatorRef: Reference to a Subject Indicator ....... -->

  <define name="subjectIndicatorRef">

    <element name="subjectIndicatorRef">

      <ref name="attlist.subjectIndicatorRef"/>

      <empty/>

    </element>

  </define>

  <define name="attlist.subjectIndicatorRef" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

    <optional>

      <attribute name="xlink:type" a:defaultValue="simple">

        <value type="NMTOKEN">simple</value>

      </attribute>

    </optional>

    <attribute name="xlink:href">

      <data type="anyURI"/>

    </attribute>

  </define>

  <!-- baseName: Base Name of a Topic .............................. -->

  <define name="baseName">

    <element name="baseName">

      <ref name="attlist.baseName"/>

      <optional>

        <ref name="instanceOf"/>

      </optional>

      <optional>

        <ref name="scope"/>

      </optional>

      <ref name="baseNameString"/>

      <zeroOrMore>

        <ref name="variant"/>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.baseName" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- baseNameString: Base Name String container .................. -->

  <define name="baseNameString">

    <element name="baseNameString">

      <ref name="attlist.baseNameString"/>

      <text/>

    </element>

  </define>

  <define name="attlist.baseNameString" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- variant: Alternate forms of Base Name ....................... -->

  <define name="variant">

    <element name="variant">

      <ref name="attlist.variant"/>

      <ref name="parameters"/>

      <optional>

        <ref name="variantName"/>

      </optional>

      <zeroOrMore>

        <ref name="variant"/>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.variant" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- variantName: Container for Variant Name ..................... -->

  <define name="variantName">

    <element name="variantName">

      <ref name="attlist.variantName"/>

      <choice>

        <ref name="resourceRef"/>

        <ref name="resourceData"/>

      </choice>

    </element>

  </define>

  <define name="attlist.variantName" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- parameters: Processing context for Variant .................. -->

  <define name="parameters">

    <element name="parameters">

      <ref name="attlist.parameters"/>

      <oneOrMore>

        <choice>

          <ref name="topicRef"/>

          <ref name="resourceRef"/>

          <ref name="subjectIndicatorRef"/>

        </choice>

      </oneOrMore>

    </element>

  </define>

  <define name="attlist.parameters" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- occurrence: Resources regarded as an Occurrence ............. -->

  <define name="occurrence">

    <element name="occurrence">

      <ref name="attlist.occurrence"/>

      <optional>

        <ref name="instanceOf"/>

      </optional>

      <optional>

        <ref name="scope"/>

      </optional>

      <choice>

        <ref name="resourceRef"/>

        <ref name="resourceData"/>

      </choice>

    </element>

  </define>

  <define name="attlist.occurrence" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- resourceRef: Reference to a Resource ........................ -->

  <define name="resourceRef">

    <element name="resourceRef">

      <ref name="attlist.resourceRef"/>

      <empty/>

    </element>

  </define>

  <define name="attlist.resourceRef" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

    <optional>

      <attribute name="xlink:type" a:defaultValue="simple">

        <value type="NMTOKEN">simple</value>

      </attribute>

    </optional>

    <attribute name="xlink:href">

      <data type="anyURI"/>

    </attribute>

  </define>

  <!-- resourceData: Container for Resource Data ................... -->

  <define name="resourceData">

    <element name="resourceData">

      <ref name="attlist.resourceData"/>

      <text/>

    </element>

  </define>

  <define name="attlist.resourceData" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- association: Topic Association  ............................. -->

  <define name="association">

    <element name="association">

      <ref name="attlist.association"/>

      <optional>

        <ref name="instanceOf"/>

      </optional>

      <optional>

        <ref name="scope"/>

      </optional>

      <oneOrMore>

        <ref name="member"/>

      </oneOrMore>

    </element>

  </define>

  <define name="attlist.association" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- member: Member in Topic Association ......................... -->

  <define name="member">

    <element name="member">

      <ref name="attlist.member"/>

      <optional>

        <ref name="roleSpec"/>

      </optional>

      <zeroOrMore>

        <choice>

          <ref name="topicRef"/>

          <ref name="resourceRef"/>

          <ref name="subjectIndicatorRef"/>

        </choice>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.member" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- roleSpec: Points to a Topic serving as an Association Role .. -->

  <define name="roleSpec">

    <element name="roleSpec">

      <ref name="attlist.roleSpec"/>

      <choice>

        <ref name="topicRef"/>

        <ref name="resourceRef"/>

        <ref name="subjectIndicatorRef"/>

      </choice>

    </element>

  </define>

  <define name="attlist.roleSpec" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- scope: Reference to Topic(s) that comprise the Scope ........ -->

  <define name="scope">

    <element name="scope">

      <ref name="attlist.scope"/>

      <oneOrMore>

        <choice>

          <ref name="topicRef"/>

          <ref name="resourceRef"/>

          <ref name="subjectIndicatorRef"/>

        </choice>

      </oneOrMore>

    </element>

  </define>

  <define name="attlist.scope" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

  </define>

  <!-- mergeMap: Merge with another Topic Map ...................... -->

  <define name="mergeMap">

    <element name="mergeMap">

      <ref name="attlist.mergeMap"/>

      <zeroOrMore>

        <choice>

          <ref name="topicRef"/>

          <ref name="resourceRef"/>

          <ref name="subjectIndicatorRef"/>

        </choice>

      </zeroOrMore>

    </element>

  </define>

  <define name="attlist.mergeMap" combine="interleave">

    <optional>

      <attribute name="id">

        <data type="ID"/>

      </attribute>

    </optional>

    <optional>

      <attribute name="xlink:type" a:defaultValue="simple">

        <value type="NMTOKEN">simple</value>

      </attribute>

    </optional>

    <attribute name="xlink:href">

      <data type="anyURI"/>

    </attribute>

  </define>

  <start>

    <choice>

      <ref name="topicMap"/>

    </choice>

  </start>

</grammar>

D A XML Schema schema for XTM 1.1 (Non-Normative)

<?xml version="1.0" encoding="UTF-8"?>

<!--

  Draft W3C XML Schema for XTM 1.1.

  First version created by Max Voskob using XML Spy. This version

  slightly modified by Lars Marius Garshol.

  TODO:

   - edit XLink support into same file

   - make it use XTM namespace

   - update with latest changes

   - make XLink attributes fixed

   - type xlink:href with anyURI

   - baseNameString and resourceData look strange

   - verify that it is correct

   - see what can be done to make schema closed (i.e: outlaw

     extensions) 

   - add xml:base

-->

<xs:schema xmlns:xlink="http://www.w3.org/1999/xlink" 

           xmlns:xs="http://www.w3.org/2001/XMLSchema" 

           elementFormDefault="qualified">

  <xs:import namespace="http://www.w3.org/1999/xlink" 

             schemaLocation="xlink.xsd"/>

  <!-- topicMap ........................................................... -->

  <xs:element name="topicMap">

    <xs:complexType>

      <xs:choice minOccurs="0" maxOccurs="unbounded">

               <xs:element ref="topic"/>

               <xs:element ref="association"/>

               <xs:element ref="mergeMap"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- topic .............................................................. -->

  <xs:element name="topic">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="instanceOf" minOccurs="0" maxOccurs="unbounded"/>

        <xs:element ref="subjectIdentity" minOccurs="0"/>

        <xs:choice minOccurs="0" maxOccurs="unbounded">

          <xs:element ref="baseName"/>

          <xs:element ref="occurrence"/>

        </xs:choice>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID" use="required"/>

    </xs:complexType>

  </xs:element>

  <!-- instanceOf ......................................................... -->

  <xs:element name="instanceOf">

    <xs:complexType>

      <xs:choice>

        <xs:element ref="topicRef"/>

        <xs:element ref="resourceRef"/>

        <xs:element ref="subjectIndicatorRef"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- subjectIdentity .................................................... -->

  <xs:element name="subjectIdentity">

    <xs:complexType>

      <xs:sequence>

        <xs:choice minOccurs="0" maxOccurs="unbounded">

          <xs:element ref="topicRef"/>

          <xs:element ref="resourceRef"/>

          <xs:element ref="subjectIndicatorRef"/>

        </xs:choice>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- topicRef ........................................................... -->

  <xs:element name="topicRef">

    <xs:complexType>

      <xs:attribute name="id" type="xs:ID"/>

      <xs:attribute ref="xlink:type"/>

      <xs:attribute ref="xlink:href" use="required"/>

    </xs:complexType>

  </xs:element>

  <!-- subjectIndicatorRef ................................................ -->

  <xs:element name="subjectIndicatorRef">

    <xs:complexType>

      <xs:attribute name="id" type="xs:ID"/>

      <xs:attribute ref="xlink:type"/>

      <xs:attribute ref="xlink:href" use="required"/>

    </xs:complexType>

  </xs:element>

  <!-- baseName ........................................................... -->

  <xs:element name="baseName">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="instanceOf" minOccurs="0"/>

        <xs:element ref="scope" minOccurs="0"/>

        <xs:element ref="baseNameString"/>

        <xs:element ref="variant" minOccurs="0" maxOccurs="unbounded"/>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- baseNameString ..................................................... -->

  <xs:element name="baseNameString">

    <xs:complexType>

      <xs:simpleContent>

        <xs:extension base="xs:string">

          <xs:attribute name="id" type="xs:ID"/>

        </xs:extension>

      </xs:simpleContent>

    </xs:complexType>

  </xs:element>

  <!-- variant ............................................................ -->

  <xs:element name="variant">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="parameters"/>

        <xs:element ref="variantName" minOccurs="0"/>

        <xs:element ref="variant" minOccurs="0" maxOccurs="unbounded"/>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- variantName ........................................................ -->

  <xs:element name="variantName">

    <xs:complexType>

      <xs:choice>

        <xs:element ref="resourceRef"/>

        <xs:element ref="resourceData"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- parameters ......................................................... -->

  <xs:element name="parameters">

    <xs:complexType>

      <xs:choice maxOccurs="unbounded">

        <xs:element ref="topicRef"/>

        <xs:element ref="resourceRef"/>

        <xs:element ref="subjectIndicatorRef"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- occurrence ......................................................... -->

  <xs:element name="occurrence">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="instanceOf" minOccurs="0"/>

        <xs:element ref="scope" minOccurs="0"/>

        <xs:choice>

          <xs:element ref="resourceRef"/>

          <xs:element ref="resourceData"/>

        </xs:choice>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- resourceRef ........................................................ -->

  <xs:element name="resourceRef">

    <xs:complexType>

      <xs:attribute name="id" type="xs:ID"/>

      <xs:attribute ref="xlink:type"/>

      <xs:attribute ref="xlink:href" use="required"/>

    </xs:complexType>

  </xs:element>

  <!-- resourceData ....................................................... -->

  <xs:element name="resourceData">

    <xs:complexType>

      <xs:simpleContent>

        <xs:extension base="xs:string">

          <xs:attribute name="id" type="xs:ID"/>

        </xs:extension>

      </xs:simpleContent>

    </xs:complexType>

  </xs:element>

  <!-- association ........................................................ -->

  <xs:element name="association">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="instanceOf" minOccurs="0"/>

        <xs:element ref="scope" minOccurs="0"/>

        <xs:element ref="member" maxOccurs="unbounded"/>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- member ............................................................. -->

  <xs:element name="member">

    <xs:complexType>

      <xs:sequence>

        <xs:element ref="roleSpec" minOccurs="0"/>

        <xs:choice minOccurs="0" maxOccurs="unbounded">

          <xs:element ref="topicRef"/>

          <xs:element ref="resourceRef"/>

          <xs:element ref="subjectIndicatorRef"/>

        </xs:choice>

      </xs:sequence>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- roleSpec ........................................................... -->

  <xs:element name="roleSpec">

    <xs:complexType>

      <xs:choice>

        <xs:element ref="topicRef"/>

        <xs:element ref="resourceRef"/>

        <xs:element ref="subjectIndicatorRef"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- scope .............................................................. -->

  <xs:element name="scope">

    <xs:complexType>

      <xs:choice maxOccurs="unbounded">

        <xs:element ref="topicRef"/>

        <xs:element ref="resourceRef"/>

        <xs:element ref="subjectIndicatorRef"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

    </xs:complexType>

  </xs:element>

  <!-- mergeMap ........................................................... -->

  <xs:element name="mergeMap">

    <xs:complexType>

      <xs:choice minOccurs="0" maxOccurs="unbounded">

        <xs:element ref="topicRef"/>

        <xs:element ref="resourceRef"/>

        <xs:element ref="subjectIndicatorRef"/>

      </xs:choice>

      <xs:attribute name="id" type="xs:ID"/>

      <xs:attribute ref="xlink:type"/>

      <xs:attribute ref="xlink:href" use="required"/>

    </xs:complexType>

  </xs:element>

</xs:schema>

E Serialization (Non-Normative)

This section provides information on how to serialize SAM instances using the XTM syntax. The main text of this specification already provides the constraints necessary to ensure interoperability, but as serialization is not entirely straightforward, this section provides additional guidance for implementors.

Ed. Note:
Needs to be written.

F Differences with XTM 1.0 (Non-Normative)

This section lists the differences between XTM 1.1 and XTM 1.0. The differences are:

·         The instanceOf element is now allowed inside the baseName element.

·         The resourceRef element is now allowed inside the parameters, instanceOf, and roleSpec elements.

Ed. Note:
Complete list.

G Resolved issues (Non-Normative)

Resolutions to the issues listed below have been proposed by the authors, but not approved by the committee. They are documented here for reference.

Issue (xtm-href-xpointer):

Does XTM allow full XPointer references, or only bare names?

Issue (xtm-href-whitespace):

Is whitespace allowed in the xlink:href attribute? If it is allowed, how is it interpreted? If it is not allowed, what action is taken when it is found?

Issue (xtm-where-resourceref):

Should resourceRef be allowed in roleSpec, instanceOf and parameters?

Issue (xtm-unused-ids):

Should we retain the id attribute on element types which do not represent something that can be reified?

Issue (xtm-version):

What version number should we give the updated XTM syntax?

Issue (xtm-normative-schema):

Which schema should be the normative schema?

Issue (xtm-xlink-actuate):

Should all or some element types which have xlink:href attributes also be given an xlink:actuate attribute? If so, what should the legal range of values be?

Issue (xtm-xmlbase-everywhere):

Should the xml:base attribute be allowed on every non-empty element type?

Issue (xtm-subjectidentity-children):

Should multiple resourceRef elements be allowed inside subjectIdentity?

Issue (xtm-variantname-deprecate):

Should the variantName element type be deprecated, and the content model of variant be adjusted to make it redundant?

Issue (xtm-parameters-deprecate):

Should the parameters element type be deprecated and replaced by scope?

Issue (xtm-schema-uri):

Should the XSDL and RELAX-NG schemas declare xlink:href attributes to be of type URI?

Issue (xtm-topicref-notopic):

Is it an error for a topicRef element to refer to a non-existing topic?

Issue (xtm-topicref-fragment):

Is the URI given in the xlink:href attribute (of topicRef elements) required to have a fragment identifier?