V5/usr/source/s4/setgid.s

Find at most related files.
including files from this version of Unix. 
/ C library -- setgid

/ error = setgid(uid);

setgid = 46.
.globl	_setgid, retrn, cerror

_setgid:
	mov	r5,-(sp)
	mov	sp,r5
	mov	4(r5),r0
	sys	setgid
	bec	1f
	jmp	cerror
1:
	clr	r0
	jmp	retrn