+#ifdef SYSV_SYSTEM_DIR
+#include <dirent.h>
+#else /* not SYSV_SYSTEM_DIR */
+#ifdef NONSYSTEM_DIR_LIBRARY
+#include "ndir.h"
+#else /* not NONSYSTEM_DIR_LIBRARY */
+#ifdef MSDOS
+#include <dirent.h>
+#else
+#include <sys/dir.h>
+#endif
+#endif /* not NONSYSTEM_DIR_LIBRARY */
+#ifndef MSDOS
+extern DIR *opendir ();
+#endif /* not MSDOS */
+#endif /* not SYSV_SYSTEM_DIR */
+