Write custom column values (keyed by contact id)

Writes cell values into one custom column, keyed by contact (row) id — the write path for externally generated data. A cell takes a string (also accepted for number, boolean and date columns and parsed against the column's type), a number, a boolean, or — for a url column only — { label, value }. Up to 500 cells per call; a value the list service refuses for the column's type answers 422 INVALID_REQUEST. updatedCount echoes how many entries were submitted, not how many cells changed.

Errors:

• 404 LIST_NOT_FOUND — The list — or the column on it — was not found for the token owner.
• 422 INVALID_REQUEST — The list service rejected one or more values for the column's type.
• 422 VALIDATION_FAILED — values missing/empty/over 500, a non-24-hex contactId, or a value in none of the accepted shapes.
• 429 RATE_LIMITED — The lists rate bucket is exhausted.

Requires one of the following token scopes: lists.