points to the specification for some element which is to be included in a schema the identifier used for the required element within the source indicated.

Include in the schema an element named p available from the current default source.

Include in the schema an element named p available from the TEI P5 1.2.1 release.

Elements are identified by the name supplied as value for the ident attribute on the elementSpec element in which they are declared. TEI element names are unique.