AcRxObject AcDbXObject AcCmComplexColor
class AcDbXObject : public AcRxObject;
dbmain.h
The original purpose of this class was to serve as a lightweight fragment of persistence, typically to be added to AcDbObjects. But this was never implemented, so now it merely serves as a parent class to AcCmComplexColor, which itself is a class that is not used by AutoCAD or the ObjectARX libraries.
Don't use this class.