2.9.334 UidSel
The UidSel structure is a 2-byte integer that identifies a user or group of users for the purpose of specifying range-level protection information about the given users. If the integer is greater than zero, it MUST be a 1-based index into the SttbProtUser at an offset of FibRgFcLcb2003.fcSttbProtUser in the Table Stream. Otherwise, it is a UID type that MUST be one of the uidEveryone, uidEditors, or uidOwners values.