Since this variable is passed to StretchDIBits, we can see what its supposed to mean.
We dont have DX5 docs, but we have docs of the current day, and this as its 'iUsage':
"Specifies whether the bmiColors member of the BITMAPINFO structure was provided and, if so, whether bmiColors contains explicit red, green, blue (RGB) values or indexes."
The second part (about what the bmiColors contains) seems redundant, since we know this is a boolean.
Source: https://learn.microsoft.com/en-us/windows/win32/api/wingdi/nf-wingdi-stretchdibits
* define MxLong/MxULong
The "long" type has different sizes on different platforms, and this may cause issues.
* use DWORD to match RegQueryValueExA arg
Now we can use our own compiled LEGO1.LIB rather than one generated from the original. Also implements a script that tests them to help ensure future commits don't break them.