All things are permissible, but not all things are beneficial; when developing an XML Schema, this is a good rule of thumb. XML Schema provides many options for developing robust, flexible data structures. One such option is the ability to define nested content model definitions.
All XML elements have a content model. A content model defines the validation rules and structure of an element’s content. Element content can consist of character data, child elements, or a mixture of both. In the cases where an element contains child elements, a content model is used to define the order, cardinality and presence of the child elements. Continue reading