The keyword char identifies a data item that has 8 bits. To the MIDL compiler, a char is unsigned by default and is synonymous with unsigned char.
In this version of Microsoft RPC, the character translation tables that convert between ASCII and EBCDIC are built into the run-time libraries and cannot be changed by the user.
The char type is one of the base types of the interface definition language (IDL). The char type can appear as a type specifier in const declarations, typedef declarations, general declarations, and function declarators (as a function-return-type specifier and a parameter-type specifier). For the context in which type specifiers appear, see IDL.
DCE IDL compilers do not accept the keyword signed applied to char types. Therefore, this feature is not available when you use the MIDL compiler /osf switch.
base_types, byte, /char, /osf, signed, string, wchar_t