// Stair ascents/descents cannot be interrupted, attempts to interrupt
        // the delay will just trash all queued delays, including travel.
        "interrupt_ascending_stairs =",
        "interrupt_descending_stairs =",

        // Stair ascents/descents cannot be interrupted except by
        // teleportation. Attempts to interrupt the delay will just
        // trash all queued delays, including travel.
        "interrupt_ascending_stairs = teleport",
        "interrupt_descending_stairs = teleport",

             mpr("Stop ascending/descending stairs.");

             mpr("Stop ascending/descending stairs.", MSGCH_DIAGNOSTICS);

        stop_delay();

        // Teleport stops stair delays.
        stop_delay(ai == AI_TELEPORT);

                    stop_delay();

                    stop_delay(ai == AI_TELEPORT);