Quick search by citation:

33 U.S. Code § 3003 - Authorized number on the active list

(a) Annual strength on active list

The annual strength of the commissioned corps in officers on the lineal list of active duty officers of the corps shall be prescribed by law.

(b) Lineal list

The Secretary shall maintain a list, known as the “lineal list”, of officers on active duty. Officers shall be carried on the lineal list by grade and, within grade, by seniority in grade.