[erlang-questions] Built In Types

[maxim minin]

Hi Erlangers,
i try to define a type "product" like:

-type product :: 'A'|'B'|'C'.

But the compiler complains"type product() already defined". 
At http://www.erlang.org/doc/reference_manual/typespec.html is "product" not in the list of built-in types. 
So i have two quetions:

Is "product" really a built-in type?
Is it possible to show all built-in types in erlang shell?

Thanks
Max