Per the description this shares the label object's text, but per its INTEGER enumeration and object name this identifies whether this dynamically-signaled tunnel is primary, backup, or unprotected within its protection scheme. An admin checks this to know which of a signaled primary/backup pair should normally be forwarding, the same logic as on static tunnels but here potentially involving fast-reroute-capable backup LSPs as well. For example, a dynamic tunnel with role backup(2) sitting idle while carrying zero traffic is expected as long as its signaled primary partner remains up.