points to the specification for an attribute or model class which is to be included in a schema the identifier used for the required class within the source indicated. indicates how references to this class within a content model should be interpreted. any one member of the class may appear a single occurrence of all members of the class may appear in sequence a single occurrence of one or more members of the class may appear in sequence one or more occurrences of one or more members of the class may appear in sequence. one or more occurrences of all members of the class may appear in sequence

If the members of the class are a, b and c, then a reference to the class within a content model is understood as being a reference to a|b|c when expand has the value alternation; to a,b,c when it has the value sequence; to (a?,b?,c?) when it has the value sequenceOptional; to (a*,b*, c*) when it has the value sequenceOptionalRepeatable; or to (a+,b+,c+) when it has the value sequenceOptionalRepeatable.

supplies a list of class members which are to be included in the schema being defined. supplies a list of class members which are to be excluded from the schema being defined.

Attribute and model classes are identified by the name supplied as value for the ident attribute on the classSpec element in which they are declared. All TEI names are unique; attribute class names conventionally begin with the latters att..