+LY_DEFINE (make_moment,"make-moment", 2,0,0, (SCM n, SCM d),
+ "create the rational number with main timing @var{n}/@var{d}.
+
+
+Moment is a point in musical time. It is consists of a pair of
+rationals (@var{m},@var{g}), where @var{m} is the timing for the main
+notes, and @var{g} the timing for grace notes. In absence of grace
+notes, @var{g} is zero.
+")