RFC 4707, "Netnews Administration System (NAS)", October 2006Source of RFC: INDEPENDENT
Errata ID: 5837
Publication Format(s) : TEXT
Reported By: Julien Élie
Date Reported: 2019-08-18
Section 6.1.2 says:
Answers of the type 1xx, 2xx, 4xx, and 5xx can have a text after the numerical code. 3xx answers contain one or more parameters with data; the exact format is explained in the description of the commands.
These sentences are not clear.
I suggest to just remove them, or reformulate them if they really have importance.
The 202 response code for VERS also has a parameter with data (the current protocol level) for instance.
And 6xx response codes are not mentioned.