Again When Keyword
A switch alternative. After the frame is displayed it is rescheduled again N1 times N2 ticks in the future. All frames in the sequence are adjusted to be identical in size (as all DMTG frames were) so that any frame overwrites any other frame.
The last frame of an animate series of items really should be a blank frame as item_read() will be clearing the screen (along with all the back buffers) a few ticks after the display sequence finishes as a part of the extended treatment needed for animated items on account of drawimage() no longer being able to predict what back buffer contains what after an animate sequence.