For eachcontainer, at most one of the following holds: thatcontainer is somedocument; thatcontainer is someterms of reference; thatcontainer is somemeeting; thatcontainer is somedocument requirements definition; thatcontainer is somechapter; thatcontainer is someproduct; thatcontainer is someECSS pre-tailoring guideline; thatcontainer is someproduct specific tailoring feedback; thatcontainer is someorganization; thatcontainer is someglossary.