ISO/IEC 13250-3:2007
(Main)Information technology — Topic Maps — Part 3: XML syntax
Information technology — Topic Maps — Part 3: XML syntax
ISO/IEC 13250-3:2007 defines an extensible markup language (XML) vocabulary for interchanging topic maps. The interpretation of the syntax is defined through a mapping from the syntax to the Topic Maps data model defined in ISO/IEC 13250-2. The vocabulary, known as XML Topic Maps (XTM) 2.0, is not designed to be extended or modified. Ease of human authoring was not a primary design goal, and consequently it is not recommended to edit the syntax directly. XTM 2.0 is a revision of the XTM 1.0 vocabulary defined in ISO/IEC 13250:2003, which was adopted verbatim from the XML Topic Maps (XTM) 1.0 specification published by TopicMaps.Org in March 2001. The differences between the two versions are described.
Technologies de l'information — Plans relatifs à des sujets — Partie 3: Syntaxe XML
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INTERNATIONAL ISO/IEC
STANDARD 13250-3
First edition
2007-03-15
Information technology — Topic Maps —
Part 3:
XML syntax
Technologies de l'information — Plans relatifs à des sujets —
Partie 3: Syntaxe XML
Reference number
ISO/IEC 13250-3:2007(E)
©
ISO/IEC 2007
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ISO/IEC 13250-3:2007(E)
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ISO/IEC 13250-3:2007(E)
Page
Contents
Foreword. iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Syntax definition. 2
4.1 About the syntax. 2
4.2 Deserialization. 2
4.3 Common syntactical constructs. 2
4.3.1 Common declarations. 2
4.3.2 The reifier attribute. 3
4.3.3 The href attribute. 3
4.3.4 Creating IRIs from strings. 3
4.4 ThetopicMap element. 3
4.5 Thetopic element. 3
4.6 TheitemIdentity element. 4
4.7 ThesubjectLocator element. 4
4.8 ThesubjectIdentifier element. 4
4.9 TheinstanceOf element. 4
4.10 Thename element. 5
4.11 Thevalue element. 5
4.12 Thevariant element. 5
4.13 Thescope element. 5
4.14 Thetype element. 6
4.15 Theoccurrence element. 6
4.16 TheresourceData element. 6
4.16.1 General. 6
4.16.2 Deserialization. 6
4.16.3 Canonicalizing embedded XML. 7
4.17 TheresourceRef element. 7
4.18 Theassociation element. 7
4.19 Therole element. 7
4.20 ThetopicRef element. 7
4.21 ThemergeMap element. 8
5 Conformance. 8
Annex A (normative) A RELAX-NG schema for XTM 2.0. 9
Annex B (informative) The XTM 2.0 DTD. 11
Annex C (informative) A W3C XML Schema schema for XTM 2.0. 14
Annex D (informative) Differences with XTM 1.0. 18
Annex E (informative) Subject identifiers for defined terms. 19
Bibliography. 20
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ISO/IEC 13250-3:2007(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 13250-3 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 34, Document description and processing languages.
This first edition of ISO/IEC 13250-3 is part of a multi-part standard. The complete series will cancel and
replace ISO/IEC 13250:2003.
ISO/IEC 13250 consists of the following parts, under the general title Information technology — Topic Maps:
⎯ Part 2: Data model
⎯ Part 3: XML syntax
⎯ Part 4: Canonicalization
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ISO/IEC 13250-3:2007(E)
Introduction
XTM (XML Topic Maps) 2.0 is a syntax for the interchange of Topic Maps. The syntax is not designed to be
extended or modified. Ease of human authoring was not prioritized during the design of XTM, and consequently it
is not recommended to edit the syntax directly.
This part of ISO/IEC 13250 should be read in conjunction with [ISO/IEC 13250-2] since the interpretation of the
XTM syntax is defined through a mapping from the syntax to the data model there defined. Informative guidance on
how to serialize instances of the data model to the XTM syntax is also provided.
XTM 2.0 is a revision of the XTM 1.0 syntax defined in [ISO/IEC 13250:2003] and [XTM1.0]. A description of the
differences between the two versions can be found in Annex D.
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INTERNATIONAL STANDARD ISO/IEC 13250-3:2007(E)
Information technology — Topic Maps —
Part 3:
XML syntax
1 Scope
This part of ISO/IEC 13250 defines an XML-based interchange syntax for Topic Maps, which can be used to
interchange instances of the data model defined in [ISO/IEC 13250-2]. It also defines a mapping from the
interchange syntax to the data model. The syntax is defined with a RELAX-NG schema, and more precision is
provided through the mapping to the data model, which effectively also defines the interpretation of the syntax.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE Each of the following documents has a unique identifier that is used to cite the document in the text. The unique
identifier consists of the part of the reference up to the first comma.
ISO/IEC 13250-2, Information technology — Topic Maps — Data model
W3C XML, Extensible Markup Language (XML) 1.0 (Third Edition), W3C Recommendation, 4 February 2004,
available at
W3C XML-Names, Namespaces in XML, W3C Recommendation, 14 January 1999, available at
W3C XPointer, XPointer Framework Version 1.0, W3C Recommendation, 25 March 2003, available at
W3C XML-Infoset, XML Information Set (Second Edition), W3C Recommendation, 4 February 2004, available at
W3C Canonical XML, Canonical XML Version 1.0, W3C Recommendation, 15 March 2001, available at
ISO/IEC 19757-2, Information technology — Document Schema Definition Languages (DSDL) — Part 2:
Regular-grammar-based validation — RELAX NG
IETF RFC 3986, Uniform Resource Identifier (URI): Generic Syntax, Internet Standards Track Specification,
January 2005, available at
IETF RFC 3987, Internationalized Resource Identifiers (IRIs), Internet Standards Track Specification, January
2005, available at
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
XTM
the syntax defined in this part of ISO/IEC13250
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4 Syntax definition
4.1 About the syntax
The acronym XTM is often used to refer to the syntax defined in this part of ISO/IEC13250. Its full name is XML
Topic Maps. The namespace for the XTM syntax ishttp://www.topicmaps.org/xtm/.
An XTM document is an XML document that conforms to the XTM syntax. This clause defines the syntax of XTM
documents using a RELAX-NG schema in compact syntax [ISO/IEC 19757-2], and their semantics using prose
describing the mapping from XTM documents to [ISO/IEC 13250-2]. The full schema can be found in Annex A, a
DTD in Annex B, and a W3C XML Schema in Annex C.
4.2 Deserialization
The process of exporting Topic Maps from an implementation's internal representation of the data model to an
instance of a Topic Maps syntax is known as serialization. The opposite process, deserialization, is the process of
building an instance of an implementation's internal representation of the data model from an instance of a Topic
Maps syntax.
This clause defines how instances of the XTM syntax are deserialized into instances of the data model defined in
[ISO/IEC 13250-2]. Serialization is only implicitly defined, but implementations should guarantee that for any data
model instance the XTM serialization produced by the implementation should when deserialized to a new data
model instance produce one that has the same canonicalization as the original data model instance, according to
[ISO 13250-4].
The input to the deserialization process is:
— A document item as defined by [W3C XML-Infoset], representing an XTM document. (Information item
properties from [W3C XML-Infoset] are referred to using [[property name]], in order to distinguish them from
properties from [ISO/IEC 13250-2].)
— An absolute IRI. This is the IRI from which the XTM document was retrieved, known as the document IRI.
This IRI shall always be provided, as it is necessary in order to assign the item identifiers of the topic items
created during deserialization. If the XTM document was not read from any particular IRI the application is
responsible for providing an IRI considered suitable.
Deserialization is done by processing each element item in the document item in document order. For each
element item encountered the operations specified in the clause for that element type are performed. An input
element item matches a clause in this document when the [[namespace uri]] property is set to
"http://www.topicmaps.org/xtm/", and the [[local name]] matches the element type name given in the title
of that clause.
Whenever a new information item is created, those of its properties which have set values are initialized to the
empty set; all other properties are initialized to null.
NOTE This part of ISO/IEC13250 requires an instance of the XML Information Set as input to the deserialization process,
but in most cases the actual input will be an XML document. This part of ISO/IEC13250 does not constrain how XML
Information Set instances are built from XML documents, but assumes that in most cases this will be done by simply using an
XML processor.
XML processors conformant to the XML Recommendation may produce different results given the same XML document,
depending on whether they are validating or non-validating, and depending on which optional features they support. Reliance on
any particular behaviour in the XML processors used by recipients is strongly discouraged.
4.3 Common syntactical constructs
4.3.1 Common declarations
The following declarations are used throughout the schema for brevity.
default namespace = "http://www.topicmaps.org/xtm/"
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namespace xtm = "http://www.topicmaps.org/xtm/"
datatypes xsd = "http://www.w3.org/2001/XMLSchema-datatypes"
start = topicMap
reifiable = attribute reifier { xsd:anyURI }?, itemIdentity*
href = attribute href { xsd:anyURI }
any-markup = (text | element * - xtm:* { attribute * { text }*, any-markup* })*
4.3.2 The reifier attribute
The reifier attribute is used to refer from the topic map construct on which it appears to the topic reifying that
construct. The reference is an IRI matching one of the topic's item identifiers.
During deserialization the value in the [[normalized value]] property of the attribute node representing the reifier
attribute is resolved into an absolute IRI following the procedure in 4.3.4. If there is a topic item with that IRI in its
[item identifiers] property, that topic item is set as the value of the [reifier] property of the topic map construct being
processed. If no such topic item exists, a new topic item is created, the IRI added to its [item identifiers] property,
and that topic item is set as the value of the [reifier] property of the topic map construct being processed.
4.3.3 The href attribute
The href attribute always references an information resource using a relative or absolute IRI valid according to
[IETF RFC 3986] and [IETF RFC 3987], but the meaning of the reference depends on context.
During deserialization the value in the [[normalized value]] property of the attribute node representing the href
attribute is turned into an IRI following the procedure in 4.3.4.
4.3.4 Creating IRIs from strings
To create an IRI from a string unescape the string by replacing %HH escape sequences with the characters they
represent, and decode the resulting character sequence from UTF-8 to a sequence of abstract Unicode characters.
The resulting string is turned into an absolute IRI by resolving it against the document IRI.
4.4 ThetopicMap element
The topicMap element type is the document element of all XTM documents. It acts as a container for the topic
map, and can be used to reify it, but has no further significance. It is declared as follows:
topicMap = element topicMap { reifiable, version, mergeMap*,
(topic | association)* }
version = attribute version { "2.0" }
The version attribute is used to specify which version of XTM the document conforms to. For XTM 2.0 documents
this shall be "2.0".
During deserialization thetopicMap element causes a topic map item to be created.
4.5 Thetopic element
The topic element type is used to represent topics, and acts as a container and point of reference for topic
information. The child elements of the topic element provide identification as well as names and occurrences,
while association roles played by the topic are specified outside thetopic element.
Thetopic element type is declared as follows:
topic = element topic { id,
(itemIdentity | subjectLocator | subjectIdentifier)*,
instanceOf?, (name | occurrence)* }
id = attribute id { xsd:ID }
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The id attribute provides a unique identifier within the document for the topic, which is used to refer to it.
During deserialization the topic element causes a topic item to be created and inserted into the [topics] property
of the topic map item.
A locator is created by concatenating the document IRI, a "#" 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
"id". This locator is added to the [item identifiers] property of the topic item. If this makes the topic item equal to
another topic item the two topic items are merged according to the procedure given in [ISO/IEC 13250-2].
4.6 TheitemIdentity element
The itemIdentity element is used to assign an item identifier to the topic map construct represented by its
parent element. It is declared as follows:
itemIdentity = element itemIdentity { href }
During deserialization the itemIdentity element causes a locator to be created from its href attribute as
specified in 4.3.3. This locator is added to the [item identifiers] property of the information item created by the
parent element. If the parent element is a topic element and this makes the topic item equal to another topic item
the two topics are merged according to the procedure given in [ISO/IEC 13250-2].
4.7 ThesubjectLocator element
The subjectLocator element is used to assign a subject locator to the topic that is represented by its parent
topic element. It is declared as follows:
subjectLocator = element subjectLocator { href }
During deserialization the subjectLocator element causes a locator to be created from its href attribute as
specified in 4.3.3 and added to the [subject locators] property of the topic item created by the parent topic
element. If this makes the topic item equal to another topic item the two topic items are merged according to the
procedure given in [ISO/IEC 13250-2].
4.8 ThesubjectIdentifier element
The subjectIdentifier element is used to assign a subject identifier to the topic that is represented by its
parenttopic element.
ThesubjectIdentifier element is declared as follows:
subjectIdentifier = element subjectIdentifier { href }
During deserialization the subjectIdentifier element causes a locator to be created from its href attribute as
specified in 4.3.3. This locator is added to the [subject identifiers] property of the topic item created by the parent
topic element. If this makes the topic item equal to another topic item the two topic items are merged according to
the procedure given in [ISO/IEC 13250-2].
4.9 TheinstanceOf element
TheinstanceOf element type is used to assign one or more types to the topic represented by its parent element.
The types are always topics, indicated by the instanceOf element's child elements. The instanceOf element
type is declared as follows:
instanceOf = element instanceOf { topicRef+ }
For each child element of the instanceOf element a topic item is produced following the procedure in 4.20. For
each topic item the following steps are then taken:
— A new association item is created, with two association role items in its [roles] property, and a topic item
representing the type-instance association type (described in [ISO/IEC 13250-2:2006], 7.2) in its [type]
property. If no such topic item exists already, one is created, and the subject identifier added to its
[subjectidentifiers] property.
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— The first association role item has its [type] property set to the topic item representing the type role in the
same association (see the section referenced above), while the [player] property is set to the topic produced
by the childtopicRef 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 [player] property is set to the
topic produced by the parent element (that is, the current topic).
4.10 Thename element
The name element type is used to add topic names to the topic represented by the parent topic element. The
child elements of thename element provide the property values of the topic name item.
Thename element type is declared as follows:
name = element name { reifiable, type?, scope?, value, variant* }
During deserialization the name element causes a topic name item to be created, and added to the [topic names]
property of the topic item created by the parenttopic element.
If the name element has an type child element it is processed according to the procedure in 4.14. Otherwise the
[type] property of the topic name item is set to the topic item whose [subject identifiers] property contains
"http://psi.topicmaps.org/iso13250/model/topic-name"; if no such topic item exists, one is created.
4.11 Thevalue element
Thevalue element type is used to provide the value of the topic name. It is declared as follows:
value = element value { text }
During deserialization the information items in the [[children]] property of the value element are traversed, and for
each character information item the Unicode character specified by the [[character code]] property is appended to
the [value] property of the topic name item created by the parentname element.
4.12 Thevariant element
Thevariant element type is used to add a variant name to a topic name. It is declared as follows:
variant = element variant { reifiable, scope, (resourceRef | resourceData) }
During deserialization the variant element causes a variant item to be created and added to the [variants]
property of the topic name item created by the name parent element. After the scope child element has been
processed, the topics in the [scope] property of the topic name item created by thename parent element are added
to the [scope] property of the variant name item.
4.13 Thescope element
The scope element type is used to assign a scope to the statement represented by the parent element. It is
declared as follows:
scope = element scope { topicRef+ }
During deserialization the scope element has no direct effect on the information set being produced, but changes
the interpretation of its child elements. Each topicRef child element is processed according to the procedure in
4.20 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.
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4.14 Thetype element
The type element type is used to assign a type to the topic map construct represented by its parent element. The
type is always a topic, indicated by thetype element's child element.
Thetype element type is declared as follows:
type = element type { topicRef }
During deserialization the child element produces a topic item following the procedure in 4.20, which is set as the
value of the [type] property of the information item produced by the parent element.
4.15 Theoccurrence element
The occurrence element type is used to assign an occurrence to the topic defined by the parent element. It is
declared as follows:
occurrence = element occurrence { reifiable,
type, scope?, ( resourceRef | resourceData ) }
During deserialization the occurrence element causes an occurrence item to be created and added to the
[occurrences] property of the topic item created by the parenttopic element.
4.16 TheresourceData element
4.16.1 General
The resourceData element type represents an information resource in the form of content contained within the
XTM document. This information resource may be either a variant name or an occurrence, and it can have a
datatype.
TheresourceData element type is declared as follows:
datatype = attribute datatype { xsd:anyURI }
resourceData = element resourceData { datatype?, any-markup }
The datatype attribute contains an absolute IRI identifying the datatype of the resource that is represented by the
resourceData element.
4.16.2 Deserialization
The resourceData element sets the [value] property of the information item created by the parent element. If the
datatype attribute is not present the [datatype] property is set to
"http://www.w3.org/2001/XMLSchema#string"; if the attribute is present the [datatype] property is set to
the value of the attribute.
If the [datatype] property is set to "http://www.w3.org/2001/XMLSchema#anyType" the procedure in 4.16.3
is followed.
If the [datatype] property is set to "http://www.w3.org/2001/XMLSchema#anyURI" the procedure in 4.3.4 is
followed to produce the value of the [value] property from the content of theresourceData element. In this case it
is an error for theresourceData element to have child elements.
Otherwise 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 information item created by the parent element. In this case it is an error for the resourceData
element to have child elements.
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