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

 Message        <Context> long float as a synonym for double is a
                language extension.

 Description    Certain standard modes allow the use of the long
                float type as a synonym for double.  This is not
                allowed by the C standard.  This message indicates
                this use of long float as a potential portability
                problem.

 User Action    Change long float to double.