Mine

	    /* !!! would/should not need to do this..  need a doubly-linked	     * list so we can go backwards.  we look through the list and	     * see if we hit the reverse previously.	     */	    for (backop=olist; (backop!=op) && (backop); backop=backop->next) {		if ((BU_STR_EQUAL(op->reg2, backop->reg1)) && (BU_STR_EQUAL(op->reg1, backop->reg2))) break;	    }	    if (backop && (backop!=op)) continue;