References

This book includes various references to Internet RFC (Request for Comments) standards and informational documents. These can be retrieved directly from the RFC Editor (at http://www.rfc-editor.org) or from the Internet Engineering Task Force (IETF, at http://www.ietf.org). RFC documents do not change after they've been published, but they can be made obsolete by new standards. The RFC Editor maintains a list giving the current status of each RFC (http://www.rfc-editor.org/rfc-index.html); it is advisable to check that an RFC is still current before beginning implementation (for example, the RTP specification RFC 1889 is under revision, and the revision will result in a new RFC that makes RFC 1889 obsolete).

In some cases it has been necessary to reference work in progress, in the form of Internet-Drafts. These are the working documents of the IETF; some are eventually published as RFCs, and others are discarded. The Internet-Drafts referenced here are expected to be available in RFC form shortly. The RFC Editor Web site has a search function that allows you to find the RFC form of these documents when published. The IETF maintains an archive of Internet-Drafts online for up to six months after their submission; at that time they must be published as an RFC, revised, or discarded.

It is important to remember that Internet-Drafts are not reference material and may change at any time. Each draft carries the following note as a reminder:

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced , or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as work in progress.

Implementing from an Internet-Draft is not wise, unless you are willing to face the possibility that the draft will change while you are writing code. In particular, it is not appropriate to ship products based on Internet-Drafts, because they may be made obsolete by the final standard.