This is the default used within Idrisi, for example.

The type can be one of ID, IDREF, IDREFS, ENTITY, ENTITIES, NMTOKEN, NMTOKENS,

The validation rule "Validation Root Valid (ID/IDREF)" is applied.

The href attribute in SOAP 1.1 (of type xs:anyURI) is called enc:ref in SOAP 1.2 and is of type IDREF.

For a formal definition of IDREF, refer to XML 1.1 [XML11].

For a formal definition of IDREF, refer to XML 1.0 [XML10].

This is a SMIL 1.0 identifier value of the form "id(" Idref ")".

IDREF and IDREFS values refer to values of other elements' ID attributes.

Legitimate values are ID, IDREF, IDREFS, ENTITY, ENTITIES, NMTOKEN, NMTOKENS, NOTATION, CDATA, and ENUMERATION.

For a formal definition of "ID", refer to XML 1.0 [XML].

For a formal definition of "IDREF", refer to XML 1.0 [XML].

This is a SMIL 1.0 identifier value of the form "id(" IDREF ")".

all IDREF or IDREFS attributes actually refer to valid IDs on the page;

For a formal definition of "IDREF", refer to XML 1.0 [XML].

For a formal definition of "ID", refer to XML 1.0 [XML].