regtail
STATIC void regtail __P((char *, char *));
regtail(ret, br); /* OPEN -> first. */
regtail(ret, br); /* BRANCH -> BRANCH. */
regtail(ret, ender);
regtail(chain, latest);
regtail(ret, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
regtail(ret, next);
regtail(regnode(BACK), ret); /* loop back */
regtail(next, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
regtail(ret, regnode(BRANCH)); /* or */
regtail(ret, next);
regtail(OPERAND(p), val);