%date.class;
Date Class Elements
Class consisting of all the types of dates permitted in this Tag Set for use inside the content model for the date-style elements, such as <history>.
Remarks
Currently, this class consists of the two types of dates: <date> and <string-date>, for use inside the content model for the date-style elements, such as <history>.
Model
<!ENTITY % date.class "date | string-date" >