Overview
ISO/IEC 13250-3:2013 specifies the XML interchange syntax for Topic Maps (XTM 2.1). It defines an XML-based representation for instances of the Topic Maps data model (see ISO/IEC 13250-2) and provides a precise mapping from that XML syntax to the data model. The XTM syntax is defined using a RELAX‑NG schema and is intended for interchange between implementations rather than manual authoring.
Key topics and technical requirements
- XTM 2.1 XML syntax: A formal XML vocabulary (namespace http://www.topicmaps.org/xtm/) covering topic map constructs such as topicMap, topic, name, occurrence, association, role, subjectIdentifier, subjectLocator, itemIdentity, resourceData, resourceRef and mergeMap.
- RELAX‑NG schema: The canonical syntax is given as a RELAX‑NG schema (compact form). Informative DTD and W3C XML Schema variants are also provided in annexes.
- Mapping to data model: The standard defines how each XTM element and attribute maps to the Topic Maps data model in ISO/IEC 13250-2; this mapping provides the authoritative interpretation of the syntax.
- Deserialization rules: Specifies how to build a data-model instance from an XML Infoset instance and a required document IRI (used for assigning item identifiers). Deserialization processes element items in document order and resolves IRIs per RFC 3986/3987.
- Identifiers and IRIs: Defines use of href, subjectIdentifier, subjectLocator, item identifiers and rules for creating absolute IRIs during processing.
- Reification and merging: Supports explicit reifier elements/attributes and mergeMap constructs to control reuse and merging of topic items.
- Conformance and canonicalization: Requires implementations to produce serializations that, when deserialized, match canonicalization expectations (see ISO/IEC 13250-4).
Applications and users
Who benefits:
- Knowledge management and semantic systems that need a standardized interchange format for topics and relationships.
- Enterprise content and metadata integration tools that import/export topic-based metadata.
- Library, archival and publishing systems managing subject-based indexes and cross-references.
- Tool vendors and implementers building Topic Maps engines, serializers/deserializers, validators, or converters between knowledge-representation formats.
Practical uses:
- Exchange of topic maps between repositories and applications
- Persisting and transporting topic-centric metadata and associations
- Interoperability between Topic Maps implementations and integration with XML toolchains
Related standards
Keywords: ISO/IEC 13250-3:2013, XTM 2.1, XML Topic Maps, RELAX‑NG, Topic Maps XML syntax, deserialization, data model mapping, IRI.
