| Field | Type | Required | Description |
|---|---|---|---|
key | String! | Yes | Required key, trimmed and lowercased. Maximum 64 characters. Normalized duplicate labels are rejected. |
value | String | No | Trimmed value, maximum 128 characters. Null or omission clears it; blank is invalid. |
color | String | No | Display color, maximum 32 characters. Null, omission or blank clears it. |