In the case of the Session class, it was to keep it light weight for use in MTDLLs. You'll have to ask MS about the other classes.

>Well, yeah.... but why? Is there some overriding reason that I can't readily grasp why MS can't incorporate the definitions of all classes in the same manner and keep them in a .vcx file? Again, it just seems like a throwback to me. DOS lives! and all that...
>
>Jim