XML Schema provides the ability to define groups of element and attribute declarations that are reusable by many complex types. Named model groups are fragments of content models, and attribute groups are bundles of attribute declarations that are commonly used together. This chapter explains how to define and reference named model groups and attribute groups.
Defining a group and reusing it many times has the advantages of
• Encouraging consistency across schema components
• Allowing the schema author to change multiple content models in only one place
• Making it obvious that certain complex types share similar children or attributes
• In many cases, making the schema less verbose