The Purpose of XML Schema Namespace RecommendationThe W3C released the Namespace Recommendation in January 1999. Namespaces are important during document validation. Different sources provide parts of a DTD in the same way that one XML schema references another. Namespaces provide a mechanism for avoiding naming conflicts.
For example, a DTD might define a
element type designed for ordinary written documents such as a book or magazine article. At some point, someone might want to add the MathML package for standardized mathematical formula mark-up. Unfortunately, MathML has a distinctlist
element type, with quite different content. There might well be a large body of existing documents, making a change to the documentlist
element type difficult. Similarly, changing the MathML element complicates the use of standardized tools to handle math.list
The solution is to have one namespace for the document DTD's element types and another for the MathML element types. A namespace-aware processor reads a revision of the original DTD that implies the first namespace, and the new MathML element types imply the MathML namespace. The XML DTD-based validator selects the correct
element type to validate against based on context. All XML schema-based processors are namespace aware, and operate this waylist