Where [1][x][y] means "smoothly decrease the period of current sample by x*16+y after each tick in the division". The ticks/division are set with the 'set speed' effect (see below). If the period of the note being played is z, then the final period will be z - (x*16 + y)*(ticks - 1). As the slide rate depends on the speed, changing the speed will change the slide. You cannot slide beyond the note B3 (period 113).
