Establishment and composition of the armed forces of the Federation
Section 217(3) · 1999 Constitution (2004 edition)
What Constitution says
(3) The composition of the officer corps an other ranks of the armed forces of the Federation shall reflect the federal character of Nigeria.
This is the 1999 Constitution as published in 2004. Later amendments aren't included yet, so a section may have changed since.
Original source
Official Gazette · CFRN 1999 official PDF · printed page 97. Original document
Release: draft-c8d50d87fae9. Source scope, review and corrections