Based on https://doomwiki.org/wiki/MUSINFO
With corrections about the use of 14100, which
is actually not supported at the moment in
ZDoom, Eternity or the original PrBoom-plus.
To maximize forwards compatiblity in case the flags in Bits/Bits2
got shifted around in different ports, both Bits and Bits2 will
accept any of the flags when using mnemonics, and they will set
their values in the corresponding bits.
However, "Bits" will only unset (set to zero) the bits in the lower
32 bits, and "Bits2" will only unset (set zero) the second 32 bits
set. This is to prevent dehacked files that only manipulate the
first 32 bits from affecting the default values from "Bits2", which
would have otherwise held hardcoded behavior expected from Doom.
