4.4BSD/usr/src/contrib/gcc-2.3.3/config/i386isc.h

/* Definitions for Intel 386 running Interactive Unix System V.
   Specifically, this is for recent versions that support POSIX;
   for version 2.0.2, use configuration option i386-sysv instead.  */

/* Mostly it's like AT&T Unix System V. */

#include "i386v.h"

/* But with a few changes.  */
#include "isc.h"