The Good Net-Keeping Seal of Approval (q.v.).
GNKSA is a set of requirements and suggestions that all newsreaders should support (considering RFCs, basic netiquette that can possibly be enforced by the program, and "user-friendliness" to certain extent).
GNKSA is the basic "quality metric" of Usenet software. Most modern newsreaders pass GNKSA/2.0 requirements.
Here's the summary (from the GNKSA 2.0 document):
- Display all essential header information
- Provide clear, separate commands for new posting, followup, and e-mail reply
- Provide cross-posting functionality
- Allow users to change essential headers
- Ensure followups and e-mail replies contain a correct Subject
- Direct followups to the correct newsgroups
- Make sure followups contain valid References
- Direct e-mail replies to the correct address
- Allow the user to change her mind about whether to post or mail
- Provide adequate quotation and attribution facilities
- Provide a user-specified "Subject: " header
- Provide a valid "From: " header
- Allow users to both cancel and supersede their own articles (and no others!)
- Try to respect the 80-character line-length conventions
- Separate signatures correctly, and don't use excessive ones
- Try to prevent obvious user errors
- Post human-readable articles unless ordered otherwise
- Provide self-protection
- Be kind to servers, leave room for others
Home page, as of writing: http://www.gnksa.org/