In SDK 1.2 or 2.1, I got the following words:

____________________________________________________
CFont:TypeUid()

Gets run-time identity of the actual font type. This enables safe casting to a derived type.

For example, if the derived type is a CFbsFont, the return value is KCFbsFontUid. You would need to cast to a CFbsFont to get a character bounding box. Similarly, a CBitmapFont returns KCBitmapFontUidVal.
____________________________________________________

But, throughout the whole SDK documents and include files, I couldn't find anything about the value of const KCBitmapFontUidVal.

Now, I really need to confirm whether it's safe to casting a CFont derived class to CBitmapFont. I got this object from CFontStore::GetNearestFontInPixels().