Both element and attribute declarations can use simple types to describe the data content of the components. This chapter introduces simple types, and explains how to define your own atomic simple types for use in your schemas.
There are three varieties of simple type: atomic types, list types, and union types.
1. Atomic types have values that are indivisible, such as
2. List types have values that are whitespace-separated lists of atomic values, such as
<availableSizes>10 large 2</availableSizes>.
3. Union types may have values that are either atomic values or list values. What differentiates them is that the set of valid values, or “value space,” ...