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.

Metadata can also be specified on metadata attributes using grouped string values. This syntax is described in Conditional processing attribute values with groups.

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