INT 41 P - MS Windows debugging kernel - "DefineDebugSegment"
AX = 0050h
BX = segment number in executable (0-based)
CX = selector
DX = instance handle
SI = segment flags (0=code, 1=data)
ES:DI -> module name of owner
Return: ???
SeeAlso: AX=0012h,AX=004Fh