Conditional processing attribute values

Conditional processing attributes use space-delimited string values or grouped string values to support both filtering and flagging.

The simplest and most common way to specify metadata on a conditional processing attribute is using individual string values. For example, the values basic and deluxe within <p product="basic deluxe"> indicate that the paragraph applies to the basic and deluxe products.

Setting a conditional processing attribute to an empty value, such as product="", is equivalent to omitting that attribute from the element.