dita — archive

[Su-Laine Yeo <syeo@justsystems.com>]

Hi everyone, Thanks Eliot for your comments. I think this issue could use wider discussion. The use of modular DTD and XSD files is essential to DITA specialization, but as far as I know we do not have an explicit statement on the syntax for linking up the modules. When one DTD module links to another DTD module, the use of public IDs and catalogs can make for an elegant and nicely-maintainable organization of files. Unfortunately however, the use of public IDs and catalogs does not entirely replace the need for directly-resolvable system IDs, because some tools can ONLY understand system IDs. Many XML tools can use a catalog to find a DTD module that is referenced by another DTD module. Neither the XML specification nor the conformance statement in the DITA specification requires tools to be able to use catalogs. Colleagues have told me that some commonly-used tool components that are not natively catalog-aware, at least not in all versions, are MSXML and Xerces. Applications that incorporate MSXML or Xerces can implement a catalog resolver if the application is developed using a compiled language such as C++ or Java. However, it is impossible to implement a catalog resolver when developing an application for certain platforms such as Internet Explorer (i.e. HTML + JScript). So the processor itself must be able to resolve references between DTD modules. Summary: If a specialized DTD references other modules, it will be usable in more tools if it includes directly-resolvable system IDs. For the DITA TC, here are some questions to consider: 1) Should the TC require that all DTDs and XSDs that it approves include directly-resolvable system IDs? We currently do this for the base DITA schemas, however I don't think we have thought about whether we will require it for specializations developed by subcommittees. 2) Should the TC (and/or Adoption TC) recommend as a best practice that specialized DTDs and XSDs include directly-resolvable system IDs? 3) For the official DTD and XSD packages in DITA 1.3 and future versions, should we try to keep the folder structure the same as in DITA 1.2 so that paths from specialized DTD and XSDs to the base DTDs and XSDs are maintained? 4) Should we provide a "flattened" version of the DITA 1.2 DTDs and XSDs so that system IDs written for DITA 1.1 will continue to work with DITA 1.2? Regards, Su-Laine Su-Laine Yeo Solutions Consultant JustSystems Canada, Inc. Office: 1 (778) 327-6356 syeo@justsystems.com XMetaL Community Forums: http://forums.xmetal.com