XML Companion, The, Third Edition

DTD limitations

XML inherited its modelling capabilities (its DTD-building instructions) directly from SGML, its older, bigger brother (see Chapter 32). This was done in order to ensure that both relevant expertise, and existing SGML-based tools, could be utilized to give the new standard an initial impetus. But even before XML was completed and released, considerable opposition to the decision to adopt SGML DTDs was raised. There were several reasons for this resistance, but criticism tended to focus on the general lack of modelling functionality in the DTD language, as well as its specific lack of support for data exchange applications, its lack of namespace sensitivity (though this is understandable, given that the Namespaces standard was ...