Examples of subject scheme maps

In this section:

1. Example: How hierarchies defined in a subject scheme map affect filtering
   This scenario demonstrates how a processor evaluates attribute values when it performs conditional processing for an attribute that is bound to a set of controlled values.
2. Example: Extending a subject scheme
   You can extend a subject scheme by creating another subject scheme map and referencing the original map using a <schemeref> element. This enables information architects to add new relationships to existing subjects and extend enumerations of controlled values.
3. Example: Extending a subject scheme upwards
   You can broaden the scope of a subject category by creating a new subject scheme map that defines the original subject category as a child of a broader category.
4. Example: Defining values for @deliveryTarget
   You can use a subject scheme map to define the values for the @deliveryTarget attribute. This filtering attribute, which is new in DITA 1.3, is intended for use with a set of hierarchical, controlled values.