unit property
Unit is the SOURCE's own id for this unit — a run-target id, a BYO worker id, a Visor machine name — so a row links straight back to the face that owns it. It is unique within a source, not across them: two planes may mint the same id, which is why (source, unit) together is the identity.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
String? unit;