Found it dicklicker.
http://www.public.navy.mil/bupers-np.../1133-010.pdfd
It's at the top of page 3.
Each male who, on or after 9 November 1979, and each
female who, on or after 1 February 1978, became a member of the
Regular Navy or Naval Reserve shall serve in the Regular Navy
and/or Naval Reserve for a total of 6 years, unless discharged
sooner. Any part of such service that is not active duty or
active duty for training shall be performed as a member of the
Naval Reserve on inactive duty.