This object reports the checksum sum for link-local LSAs on an OSPF virtual link's link-local database, used per the description to detect database changes and to compare consistency specifically between the virtual neighbors at each end of that virtual link. It matters for the same reason as its physical-interface counterpart, scoped to virtual-link troubleshooting; if the two routers terminating a virtual link report differing values here, that specific logical adjacency has an LSA sync problem distinct from anything happening on the physical interfaces underneath it.