Identifiers can be up to 255 characters long, and must conform to C-style syntax. MkTypLib is case sensitive, but it generates type libraries that are case insensitive. It is therefore possible to define a user-defined type whose name differs from that of a built-in type only by case. User-defined type names (and member names) that differ only in case refer to the same type or member. Except for property accessor functions, it is invalid for two members of a type to have the same name, regardless of case.