VMS Help CC, Messages, BOOLEXT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Message        The _Bool data type is a new feature in the C99
                standard.  Other C compilers may not support this
                feature.

 Description    This is a new language feature in C99.  While having
                a standard specification for portability, the feature
                may not yet be available in all of the compilers you
                use.

 User Action    Determine whether or not the use of this feature will
                cause portability problems for this code.