This object specifies the type of recovery disjointness required between this tunnel and its protecting backup -- none, link, node, srlg, or unknown -- as the description states. This determines how strictly the network guarantees the backup path avoids sharing infrastructure with the primary: srlg (shared risk link group) disjointness is the strongest guarantee, ensuring even fiber bundled in the same conduit as the primary isn't reused by the backup, which matters for surviving a single fiber cut affecting multiple seemingly-separate links. For example, node(3) disjointness ensures the backup path avoids every router the primary path passes through, protecting against a single router failure even without guaranteeing physically separate fiber routes.