The sprite that has no width and no height, which draws nothing. The sprite numbers 00 and 01 both find it: 00 is the one that an object has when it is not there, and 01 is the one that an object is given to take it away. Every sprite starts with its width in bytes, in bits 0 to 3 (bits 6 and 7 hold whether it has been flipped from left to right and top to bottom, and are changed by FlipSprite as the objects are drawn), and its height in lines. The pixels follow, one line at a time and from the bottom line to the top, with a pair of bytes for each byte of the line. The first byte of a pair is the mask, which has a bit set for every pixel that is cleared, and the second is the data, which has a bit set for every pixel that is set. The sprites are found from their sprite numbers by the table at SpritePointers.