RFC 8914 - RPZ extended errors
Per-RPZ-zone configuration to pick EDE code returned for blocked requests configured in a particular RPZ policy:
none
No Extended DNS Error code is set (default).
forged
Extended DNS Error code 4 - Forged Answer.
blocked
Extended DNS Error code 15 - Blocked.
censored
Extended DNS Error code 16 - Censored.
filtered
Extended DNS Error code 17 - Filtered.
prohibited
Extended DNS Error code 18 - Prohibited.