After some investigation it appears that this feature is case insensitive. I wrote a class cString (before porting to the microsoft c compiler) with a member char *m_text. When I added the appropriate bit in autoexp.dat:
The debugger displays ??? when I move the mouse over a variable of this type. I tested this by writing a new class called TestString with the same member type and it worked in this case.
I guess this means I will have to rename my type for it to work under the debugger.
I am used to directly watching the return value from functions in the Watch window in VC5. But now I see that there is no such facility in VC6 debugger. Is it like a feature which should be turned on???.