set of VERSIONS referring to the same DATA SYSTEM and belonging to the same TYPE OF FRAME

Note 1 to entry: A FRAME may be restricted by VALIDITY CONDITIONs.

Note 2 to entry: In IFOPT, used to group elements such as STOP PLACEs, STOP PLACE SPACEs and PATH LINKs into a common model version when each item does not have its own version.