46 C.F.R. § 30.10-71
Tank vessel endorsements—TB/ALL
The following ratings are established in part 13 of this chapter. The terms for the ratings identify persons holding valid endorsements for service in the ratings issued under that part:
(a) Tank Vessel-PIC.
(b) Tank Barge-PIC.
(c) Restricted Tank Vessel-PIC.
(d) Restricted Tank Barge-PIC.
(e) Tank Vessel-Assistant.
(f) Tank Vessel-Engineer.