what is the .v in my.v -= 30 * time;

what does the .v stand for
ive seen my.x,my.y and my.z
its from the waterfall code


my.v -= 30 * time;

u and v are the skin coordinates.
So my.v -=30 *time... skin will be moving along object.
u is horizontal move
v is vertical

thanks fro ur reply
5 stars for u

but u shouldn't use u and v...better is if u use the u and v shader from the templates