ISO/IEC JTC 1/SC34 N0310



Information Technology --

Document Description and Processing Languages

Title: Requirements for Detailed Descriptions of Differences between XTM 1.0 DTD and HyTime-based meta DTD
Source: SC 34 Japan
Project: Topic Map Models
Project editors:  
Status: Draft
Date: 17 May 2002
Distribution: SC34 and Liaisons
Refer to: 220, 238,239, 260,277
Reply to: Dr. James David Mason
(ISO/IEC JTC1/SC34 Chairman)
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Ms. Sara Hafele, ISO/IEC JTC 1/SC 34 Secretariat
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Requirements for Detailed Descriptions of Differences between XTM 1.0 DTD and HyTime-based meta DTD


The ISO/IEC JTC 1/SC34 N0277 draft document outlines the differences between the HyTime-based meta-DTD, and the XTM DTD of ISO/IEC 13250:2000. Here, requirements for further clarification of N0277, including prose details about the XTM 1.0 DTD is proposed. This document follows the sequence of selected topics described in N0277.


1. Description of HyTime-based Topic Maps meta-DTD found in ISO 13250:2000 and the XTM 1.0 DTD syntaxes in prose

Before an instance of one syntax can be transformed into an instance of an underlying model, the syntax should be formally documented. The prose description of HyTM is documented in ISO/IEC 13250:2000; that of XTM 1.0 DTD is not. The syntax of XTM 1 DTD shall be defined in prose.

2. Addressing

The method of addressing in XTM shall be formally documented; this may or may not be limited to Uniform Resource Indicators (URI).

3. Architectural forms versus fixed DTDs

Reasoning for the choice of a fixed set of each of the elements types for the XTM 1.0 DTD over the The HyTime-based meta-DTD as a set of architectural forms, or visa versa, needs clarification. The differences between an architectural versus interchange syntax is critical to the development of all Topic Map standards; all underlying models depend on it. This should be described in detail. This difference between an architectural form versus a fixed syntax may be sufficient for the XTM 1.0 DTD to be included as an informative annex rather than a normative one in ISO/IEC 13250:2000.

4. Hytime-specific features removed

This is as described in N0277 and needs no further discussion.

5. The XTM DTD prefers element types to attributes

The design choices for each respective syntax, an architectural or fixed interchange syntax, as described in N0227 needs no further clarification, unless further design work to revise either DTD is decided on.

6. The XTM DTD generalizes "display name" / "sort name" as "variant name"

The generic method to "add variant names to topics for any processing context by defining parameters that describe and/or identify that processing context" by XTM are referenced as display and sort published subjects. These are part of the core published subjects are not formally included with the XTM 1.0 DTD in the specification. The handling of sort name and display name in XTM 1.0 DTD must be addressed.

7. Link syntax differs

This is as described in N0277 and needs no further discussion.

8. XTM provides for subject-constituting resources.

Since the XTM DTD "boosts the notion of subject constituting resources to fully equal status with subject indicating resources," in contrast to the the HyTime-based meta-DTD that only "declares the use of subject-indicating resources to declare the subjects of topics," it may be advisable to align one with the other for the sake of future standards work or describe the reasoning behind maintaining this difference.

9. Types of referencing elements in the XTM DTD.

Definitions of <topicRef>, <resourceRef> and <subjectIndicatorRef> and examples on how to use them, should be provided.

10. Facets are not mentioned in the XTM DTD.

Examples on how a topic map author might use XTM syntax to "explicitly regard an information object as a subject in itself (a subject constituting resource)" and "associate properties and values with information objects by means of <association> elements, and how this is similar to but somewhat different from how the facets in HyTime-based meta-DTD act as qualifiers to "assign a property (and value for the property) to an information object" should be provided.

11."Public subject" renamed "published subject"

A formal definition shall be provided. The detailed requirements from the Published Subjects Technical Committee of OASIS shall be submitted and reviewed for inclusion.