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Deprecating the "X-" Prefix and Similar Constructs in Application Protocols

Approval announcement
Draft of message to be sent after approval:


From: The IESG <>
To: IETF-Announce <>
Cc: RFC Editor <>
Subject: Protocol Action: 'Deprecating the X- Prefix and Similar Constructs in Application Protocols' to Best Current Practice (draft-ietf-appsawg-xdash-05.txt)

The IESG has approved the following document:
- 'Deprecating the X- Prefix and Similar Constructs in Application
  (draft-ietf-appsawg-xdash-05.txt) as Best Current Practice

This document is the product of the Applications Area Working Group.

The IESG contact persons are Pete Resnick and Barry Leiba.

A URL of this Internet Draft is:

Ballot Text

   Technical Summary 

Historically, designers and implementers of application protocols 
have often distinguished between "standard" and "non-standard" 
parameters by prefixing the latter with the string "X-" or similar 
constructions.  In practice, this convention causes more problems 
than it solves.  Therefore, this document deprecates the "X-" 
convention for newly defined textual parameters in application 

   Working Group Summary 

The WG discussed the scope of the document, in particular if it 
intends to change any existing IANA registries which use "X-" 
namespace (or similar) and whether it applies to registries that 
use numeric values. As per WG discussion, the answer to both 
questions above is "no" and the document was clarified to reflect 

   Document Quality 

The document doesn't define a protocol. At least 1 specification already 
voluntarily conforms to the recommendations specified in the document.


Alexey Melnikov <> is the document shepherd.
Pete Resnick <> is the cognizant AD.

RFC Editor Note