This is the MPLS label this device pushes on outbound packets for the forward direction of this co-routed tunnel, manually assigned since there's no signaling protocol to negotiate it. An admin ensures this exactly matches the next-hop router's expected incoming label for the forward leg, since a mismatch here breaks the outbound half of the circuit even if the reverse label is correctly configured. For example, this device pushing forward label 200 while the next hop expects 202 will blackhole outbound traffic on this tunnel while the return path (using the separate reverse-in-label) continues working, producing a one-way-only symptom.