This read-only FcList is a bitmap, copied from the zoneAliasList object in the zoneTable at the time the currently active zone set was activated, identifying which aliases form this zone as it is presently enforced. Admins use it to see the frozen snapshot of alias membership that's actually in effect, separate from whatever the zone's live configuration might now say. For example, an admin who recently changed an alias's members would compare this enforced list to the current zone configuration to see whether the change has been activated yet.