Bolt.Sips v1.2.1-rc2 Bolt.Sips.Types.UnboundRelationship View Source
Self-contained graph relationship without endpoints. An UnboundRelationship represents a relationship relative to a separately known start point and end point.
https://github.com/boltprotocol/boltprotocol/blob/master/v1/_serialization.asciidoc#unboundrelationship