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

 Message        This redeclaration of "<name>" specifies a different
                extern model than a previous declaration of the
                variable at <location>.

 Description    Two declarations of the same variable use different
                extern models.  The extern model is specified by a
                #pragma extern_model directive that appears before
                the declaration in the source.  This redeclaration
                may cause unexpected behavior.

 User Action    All declarations of a variable should use the same
                extern model.