lojix/wam_prolog/src/main/com/thesett/aima/logic/fol/wam/machine/WAMResolvingJavaMachine.java
private void trail(int addr)
    {
        // if (a < HB) \/ ((H < a) /\ (a < B))
        if ((addr < hbp) || ((hp < addr) && (addr < bp)))
        {
            //  TRAIL[TR] <- a
            data.put(trp, addr);

            //  TR <- TR + 1
            trp++;
        }
    }
private void trail(int addr)
    {
        // if (a < HB) \/ ((H < a) /\ (a < B))
        if ((addr < hbp) || ((hp < addr) && (addr < bp)))
        {
            //  TRAIL[TR] <- a
            data.put(trp, addr);

            //  TR <- TR + 1
            trp++;
        }
    }
Records the address of a binding onto the 'trail'. The trail pointer is advanced by one as part of this
operation.

@param addr The binding address to add to the trail.