THE XML REVOLUTION - TECHNOLOGIES FOR THE FUTURE WEB

Overview of XML Schema

The most central top-level constructs:

a (global) element declaration associates an element name with a type
a complex type definition defines requirements for attributes, sub-elements, and character data in elements of that type
- attribute declarations: describe which attributes that may or must appear
- element references: describe which sub-elements that may or must appear, how many, and in which order
a simple type definition defines a set of strings to be used as attribute values or character data

(Two types or two elements cannot be defined with the same name, but an element declaration and a type definition may use the same name.)

An element in an XML document is valid according to a given schema if the associated element type rules are satisfied.

If all elements are valid, the whole document is called valid. (Unlike DTD, there is no way to require a specific root element.)