Nintendo DMG-01 - Game Boy Console Manual page 26

2.8.2. Sprites
To display a sprite in the upper left corner of the
screen set sprite X=8, Y=16.
Only 10 sprites can be displayed on any one line.
When this limit is exceeded, the lower priority
sprites (priorities listed above) won't be displayed.
To keep unused sprites from affecting onscreen sprites
set their Y coordinate to Y=0 or Y=>144+16. Just
setting the X coordinate to X=0 or X=>160+8 on a
sprite will hide it but it will still affect other
sprites sharing the same lines.
Blocks have the following
format:
Byte0 Y position on the screen
Byte1 X position on the screen
Byte2 Pattern number 0-255 (Unlike some tile
numbers, sprite pattern numbers are unsigned.
LSB is ignored (treated as 0) in 8x16 mode.)
Byte3 Flags:
Bit7
Bit6
Bit5
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Priority
If this bit is set to 0, sprite is
displayed on top of background & window.
If this bit is set to 1, then sprite
will be hidden behind colors 1, 2, and 3
of the background & window. (Sprite only
prevails over color 0 of BG & win.)
Y flip
Sprite pattern is flipped vertically if
this bit is set to 1.
X flip
Sprite pattern is flipped horizontally
if this bit is set to 1.
TM
Game Boy CPU Manual
V 1.01