The   PEN_CHECKING_STYLE   attribute   selects    the    desired
  compile-time and link-time checking to perform when the generate
  environment file is inherited.

     PEN_CHECKING_STYLE( option )

      COMPILATION_TIME  Uses the compilation time of the environment
                        file in all subsequent compile-time and link-time
                        checking for users of this environment file.
                        This is the default.
      IDENT_STRING      Uses the [IDENT()] string of the environment file
                        in all subsequent compile-time and link-time
                        checking for users of this environment file.
      NONE              Disables all compile-time and link-time checking
                        for users of this environment file.