status summary exclusions

Q Where does a status field's "Excluded statuses" setting (Summary = Status) show over REST, is it writable, and does _summarize honour it?

Endpoint GET /schema/Shot/fields/sg_status_list ; PUT /schema/Shot/fields/sg_status_list ; POST /entity/shots/_summarize

Docs claim The Flow PT 8.88 administrator help describes the setting in the web interface. The REST docs are silent.

Actual

GET /schema/<Type>/fields/sg_status_list, site and ?project_id=<sandbox>, Shot and Asset:
  properties [default_value, display_values, hidden_values, summary_default, valid_values]; "exclu" in the body: False
  GET /schema/Shot/fields?project_id=... and /api/v1.1/...: "exclu" in the body: False
  GET /schema/DisplayColumn -> 404 "Entity type 'DisplayColumn' does not exist."
the event log, Shotgun_DisplayColumn_Change, entity {"type": "DisplayColumn", "name": "sg_status_list"}, project null
  old data_type_properties {"status_list_default": "wtg", "status_list_subset": [...], "status_list_format": null}
  new data_type_properties {..., "status_list_summary_exclude": ["omt"]}
PUT /schema/Shot/fields/sg_status_list {"properties": [{"property_name": "status_list_summary_exclude", ...}]}
  -> 400 "API schema_field_update() invalid property 'status_list_summary_exclude': ...
          Valid property names: ["name", "visible", "description", "summary_default", "default_value",
          "valid_values", "custom_metadata"]"

the probe's own two Shots, one fin, one omt (--write):
  both          status_list "fin" over 2 rows
  the omt one   status_list "na"  over 1 row
  the fin one   status_list "fin" over 1 row
the sandbox's existing Shots (wtg 13, ip 14, fin 1, rev 7, omt 1):
  status in [fin, omt] -> "fin";  [ip, omt] -> "ip";  omt alone -> "na";  control [fin, wtg] -> "ip"
  status_percentage and status_percentage_as_float: 0 on every set

Teaches

• The setting is stored where REST cannot read it. It is status_list_summary_exclude inside the field's DisplayColumn data_type_properties, and DisplayColumn is not a REST type. It is site-wide: the change event names no project, and the schema reads the same with and without project_id.
• The one REST trace is Shotgun_DisplayColumn_Change in the event log, whose meta.new_value holds the list. A client can learn the current list only from the newest such event, if the log still has it.
• Not writable. PUT /schema rejects the name and enumerates the seven writable properties, so the exclusion is set in the web interface only (Fields, the status field, Summary = Status, Excluded statuses).
• status_list applies it. Without an exclusion a mix rolls up to ip (probe 079: [fin, wtg] gives ip); with omt excluded, [fin, omt] gives fin, and omt alone gives na, not omt. A client computing its own roll-up from grouped counts must drop the excluded statuses itself, and has to be told which they are.
• status_percentage returned 0 on every set here and is not a share of anything (probe 079).