Design of Modular XML documents

EXtensible Markup Language (XML) documents may have a complex structure. Many such documents have a design that can be customized by the document author, either by extension, redefinition of components, or selection of just a subset of the allowed components. The design of a document to accomodate such changes can be quite difficult.

The document structure can be arranged in a modular fashion, with minimal interaction between the modules. This simplifies both the design and the customization processes. We discuss these modular designs, and show examples of realizing them in Document Type Definitions.