/ANSI_ALIAS
     /NOANSI_ALIAS (D)

  Directs the compiler to assume the ANSI C aliasing rules, thus
  giving it the freedom to generate better optimized code.

  The aliasing rules are explained in Section 3.3, paragraphs 20 and
  25 of the ANSI C Standard.

  The default is /NOANSI_ALIAS for the /STANDARD=VAXC and
  /STANDARD=COMMON compiler modes.  The default is /ANSI_ALIAS for
  all other modes.