Expectations for conditional processing

Certain behaviors are expected of processors when working with conditional processing.

Processors SHOULD be able to perform filtering and flagging using the following attributes: @props, @audience, @deliveryTarget, @platform, @product, and @otherprops.

The @props attribute can be specialized to create new attributes, and processors SHOULD be able to perform conditional processing on specializations of @props.

Although metadata elements exist with similar names, such as the <audience> element, the specification does not define any mechanism for conditional processing using metadata elements.