A node reference without version means "the resource as it is now". With version it is immutable. It is the DAG-CBOR form of the mutable URL hm://<space>/<node>?v=<version>, and of the bare hm://<space>?v=<version> when node is omitted; the forms convert exactly. Redirect targets, comment targets, link targets, policy scopes and RPC inputs all use it, so moving or renaming a resource never breaks any of them. The version is ignored where a reference names an audience, as in the readers audience.

References are hm://<space>/<path> strings, sometimes with ?v=. A move breaks every one that was not pinned. Stem writes links with both the path and the node id (see Placement) and stores the id in records.