The documentation says that BGCHK should return Rotation, Scaling, Color, and Variable animation states in bitmasks 16, 32, 64, and 128 (corresponding to #CHKR, CHKS, #CHKC, and #CHKV). However, in reality it uses bitmasks 4, 8, 16, and 32, so those built-in constants cannot be used.
Oh, even the constants are wrong? Jeez, how did they not catch that? That's like a basic thing to catch; don't they have a code suite which tests all these? Does nobody unit test?
The constants are for sprites -- those work fine. However, BGs don't have Definition or UV animation, so that explains the discrepancy.
The manual now says that BGCHK uses 4, 8, 16, and 32 (I'm not sure if it was always like this, or if they fixed it at some point)
It does still claim that #CHKR/S/C/V have the values 4, 8, 16, and 32 though, even though they are really 16, 32, 64, and 128.
