Correct. From Article 2, paragraph B of the Legion Charter;
B. Upon admission, members are assigned a unique four-digit identification number following in the tradition of the stormtrooper character, TK-421, mentioned in A New Hope. Preceding this number is a two-character prefix code denoting the costume of the member. The prefix codes and what costumes they identify are listed below. Members owning more than one costume still have only one identification number but are referred to using whatever prefix codes are applicable. Identification numbers will be maintained by the Legion Membership Officer and are permanently assigned. If members convert to inactive status, their numbers will be retired until such time as the member returns to active status.
(underline added by me for clarity)