equiv
static void equiv(struct line *, int, struct line *, int, int *);
equiv(sfile[0], slen[0], sfile[1], slen[1], member);
wint_t equiv[NCHARS_SB]; /* equivalence set */
s->equiv[0] = backslash(s, NULL);
s->equiv[0] = wc;
src[0] = (char)s->equiv[0];
s->equiv[p++] = i;
s->equiv[p] = OOBCH;
s->set = s->equiv;