The ZeeRex DTD

1. Introduction
2. Current Version
3. Older Versions
4. Documentation

1. Introduction

The ZeeRex SGML DTD is maintained by Rob Sanderson <azaroth@liverpool.ac.uk> based on exensive discussions with the ZeeRex working group. It is a specification for how to represent metadata describing a single database.

Up to and including version 1.6 of the DTD, the ZeeRex specifications were known by the name ``Explain--'', so all the versions of the DTD up to that point are named accordingly. From version 1.7 onwards, the name changes to ZeeRex.

The ZeeRex XML schemas from version 1.7 onwards are uniquely identifed by the URIs http://explain.z3950.org/dtd/version/ - for example, version 2.0 of the schema has the identifier URI http://explain.z3950.org/dtd/2.0/

2. Current Version

The definitive rendition is the SGML DTD, but for convenience, we also provide the specification in two other formats: an XML DTD, produced automatically by a trivial sed script; and an XML Schema, produced automatically by Connolly, Bos, Koite and Holstege's Perl script dtd2xsd.pl.

The current version of the SGML DTD is v2.0.
  Other formats: [XML DTD] [XML Schema]

3. Older Versions

If you want to track the evolution of ZeeRex, you may be interested in the earlier versions of the DTD, and the changes between those versions:

• version 1.0, proposed on Wed, 6 Mar 2002 13:20:54
    Other formats: [XML DTD] [XML Schema]

• version 1.1 [changes] (Thu, 7 Mar 2002 13:54:04)
    Other formats: [XML DTD] [XML Schema]

• version 1.2 [changes] (Fri, 8 Mar 2002 17:28:15)
    Other formats: [XML DTD] [XML Schema]

• version 1.3 [changes] (Tue, 12 Mar 2002 11:50:12)
    Other formats: [XML DTD] [XML Schema]

• version 1.4 [changes] (Fri, 22 Mar 2002 19:52:36)
    Other formats: [XML DTD] [XML Schema]

• version 1.5 [changes] (Thu, 28 Mar 2002 20:36:36)
    Other formats: [XML DTD] [XML Schema]

• version 1.6 [changes] (Fri, 29 Mar 2002 20:18:39)
    Other formats: [XML DTD] [XML Schema]

• version 1.7 [changes] (Mon, 29 Apr 2002)
    Other formats: [XML DTD] [XML Schema]

• version 1.8 [changes] (Thu, 29 Aug 2002 11:02:04)
    Other formats: [XML DTD] [XML Schema]

• version 1.9 [changes] (Fri, 6 Jun 2003 17:39:55)
    Other formats: [XML DTD] [XML Schema]

• version 2.0 [changes] (Thu, 26 Feb 2004 12:18:11)
    Other formats: [XML DTD] [XML Schema]

4. Documentation

We also maintain:

• The ZeeRex DTD Commentary, explaining the structure of ZeeRex records and giving rationales for some of the decisions that we took in arriving at the current version.

• The ZeeRex DTD Reference Guide, an element-by-element and attribute-by-attribute walkthrough of the DTD which documents every non-obvious part.
  [NOTE: the Reference Guide is out of date and may be deleted in the future, as the commentary provides a more digestible and up to date form of essentially the same information.]

• The ZeeRex DTD FAQ, answering some specific questions that have arisen concerning the DTD and how to describe databases with it.

• Extensions to ZeeRex Records, a description of when and how to extend the record, and why you probably shouldn't.

• Validating ZeeRex Records, including the stable URLs and FPIs for various versions of the ZeeRex specification, and guidance for establishing a link between a ZeeRex record and the appropriate version of the DTD.