English: Post type key. Must not exceed 20 characters and may only contain lowercase alphanumeric characters, dashes, and underscores. See <a href="https://developer.wordpress.org/reference/functions/sanitize_key/" target="_blank">sanitize_key()</a>.
Dutch: Berichttype sleutel. Mag niet langer zijn dan 20 tekens en mag alleen kleine alfanumerieke tekens, streepjes en underscores bevatten. Zie <a href="https://developer.wordpress.org/reference/functions/sanitize_key/" target="_blank">sanitize_key()</a>.