The user every read and write runs as.
Compute-only: an onLookupMiss: 'create' miss is previewed, not created.
OptionalFieldThe mapping's foreign-key lookup settings per field.
OptionalHumanDecides which current values a person entered; absent = no guard.
Positive lookup hits shared by every record of the run (CanCacheLookups).
The caller's provider: foreign-key lookups (and a lookup row created on a miss) run on it, outside the unit.
Overwrite values a person entered.
The write-back unit's provider (MetadataProviderCapabilities.RunIsolated): every read, save and the transaction run on it.
The processed record.
The result being built; the writer fills its write fields.
OptionalWithheldWithheld targets: the guard always decides a withheld field (without one it is kept), and its Human value is never retired.
What an OutputMappingWriter writes for.