attribute attribute-name element-qualifier*
     ((item | @) numeric-expression)? (is | isnt)
     (cdata | name | names | number | numbers | nmtoken |
       nmtokens | id | idref | notation | entity | entities | group)

You can use the attribute is test to determine whether an attribute is of a specified type. For example, the following code will succeed if attribute "foo" is of type "name", and will fail otherwise:

  attribute "foo" is name

Attribute type tests can be combined by joining the types with or (|) and parenthesizing them. Note that for a data attribute, a test of its type for id, idref, idrefs, notation, entity, or entities will always fail because those types of attributes cannot be associated with a notation.

Entity and notation attribute tests can be applied directly to attribute values which are declared as entity or notation, or directly to an item of an attribute declared as entities.