Normally, the Windows API provides both A (ANSI) and W (wide-character) versions of most functions. On Windows 95/98/Me, only the "A" versions are implemented and attempting to call a "W" version will fail with an error code that indicates that the function is unimplemented. On the Windows NT line of operating systems, both the "A" and "W" versions are implemented (however, the operating system generally only internally implements the "W" version natively, and the "A" version is usually a translation thunk to the "W" version).