Technically not since ~2000. Windows uses UTF-16 throughout the OS. That is, Windows strings will be encoded and decoded as UTF-16 not UCS-2. However the trick

Technically not since ~2000. Windows uses UTF-16 throughout the OS. That is, Windows strings will be encoded and decoded as UTF-16 not UCS-2. However the tricky bit is that the kernel doesn't enforce this so it's possible for programmers to intentionally make broken UTF-16 strings. A broken UTF-16 string shouldn't be considered UCS-2 just because it happens to be a valid UCS-2 string (otherwise all bit patterns could be called "UCS-2" so long as they are an even number of bytes in length).