Organization API key. Keys are prefixed with vk_live_ (production) or
vk_sandbox_ (sandbox).
Identity type ID (idtype_*).
API version date string (e.g. 2026-02-01). If omitted, the version
pinned to your API key is used.
Response key casing. Defaults to snake.
Unique key for idempotent requests. Cached for 24 hours. Sending the
same key with different parameters returns 422.
Machine-readable field name.
Human-readable label.
Allowed values when field_type is enum.