Defines an internal command \graduation@date that is referenced by:

The purpose of the \providecommand is to insure that \graduation@date is defined, so that both explicit and default definitions can use \renewcommand.

nmtthesis2015.sty
%
% - - -   \ g r a d u a t i o n d a t e
%
{%

This command is optional, so we also define a default \graduation@date command that uses the current month and year to guess the date. This command assumes that months 1–5 imply a May graduation date; months 6–8, August; and months 9–12, December.

The commands \month and \year are Plain TeX. I could not find any LaTeX equivalents.

nmtthesis2015.sty
%
% - - -   \ g r a d u a t i o n @ d a t e
%