This bitmask indicates the presence and status of labels indicated by the mplsTunnelARHopExpLabel and mplsTunnelARHopExpRvrsLabel objects. For the Present bits, a set bit indicates that a label is present for this hop in the route. For the Global bits, a set bit indicates that the label comes from the Global Label Space. A clear bit indicates that this is a Per- Interface label. A Global bit only has meaning if the corresponding Present bit is set.