This pre-processor constant yields true when used on a DEC alpha processor and NaN otherwise.

Since MSIE only runs on Macintosh and Windows platforms, and a DEC alpha is not a Macintosh, there is an implication here that this will be true only when MSIE is running on Windows NT on a DEC alpha. It should also be the case that the @_win32 directive returns true as well.

If you intend to hide this directive inside some comments, it must be done like this:

/*@_alpha @*/