XML Companion, The, Third Edition

Including other models

Within DTDs, parameter entities are often used to reference external document model components. For example, a commonly used table model, such as the CALS or HTML model, is often referenced from numerous document models that need to include tables. While general entities (see Chapter 4) can be used in all XML documents, and therefore in XML Schema documents, it is not necessary to rely upon this feature. The XML Schema standard has its own capabilities for sharing models.

Schema-switching

As already described, it is possible to let the XML processor do all of the work of including other models, using namespaces and the Any element (or the AnyAttribute element) to identify the namespace of the other model, and the valid ...