cannot initialize WNDCLASSW, WNDCLASSEX, WNDCLASSEXW window structs

[rsk82]

WNDCLASS wc; - ok
WNDCLASSA wc; - ok
WNDCLASSW wc; - Error: undefined identifier WNDCLASSW, did you 
mean alias WNDCLASS?
WNDCLASSEX wc; - Error: undefined identifier WNDCLASSEX, did you 
mean struct WNDCLASSEXA?
WNDCLASSEXA wc; - ok
WNDCLASSEXW wc; Error: undefined identifier WNDCLASSEXW, did you 
mean struct WNDCLASSEXA?

code:

import core.runtime;
import core.sys.windows.windows;
extern(Windows)
int WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR 
lpCmdLine, int iCmdShow) {
  WNDCLASSEXA wc;
  return 0;
}

I most concerned about WNDCLASSEXW, that is the version I intend 
to use.