- “Obsoletes xxxx”指的是此替代的其他RFC。
- “更新xxxx”是指其他只更新但不替换的RFC。
但这引出了一个问题......为什么RFC会更新另一个RFC而不替换它？
“更新”是否意味着某些早期信息在较旧的RFC中是矛盾的，但其他信息仍然是标准的？这看起来很奇怪。
答案 0 :(得分：2)
“Updates xxxx”只是为现有RFC添加了定义。现有RFC的内容不会被新RFC无效，仍然需要实现该协议。例如，如果不需要重新定义完整的协议，但需要进行一些澄清。
“Obsoletes xxxx”是协议的完全重新定义。如果不是出于其他原因，则无需阅读已废弃的RFC以了解/正确实施协议。
答案 1 :(得分：2)
条款更新和过时过去由RFC 2223定义，但RFC 7322已废弃，但不会明确定义这些术语。
我认为较早的RFC在定义这些术语方面做得很好。
RFC 2223,1543和1111，它们都是必不可少的＆＃34; RFC作者的指令＆＃34;，将这些术语定义为＆＃34;与其他RFC的关系＆＃34;。 RFC 825是一个非常早期的版本，并没有定义术语。
6. Relation to other RFCs
Sometimes an RFC adds information on a topic discussed in a previous
RFC or completely replaces an earlier RFC. There are two terms used
for these cases respectively, Updates and Obsoletes. A document that
obsoletes an earlier document can stand on its own. A document that
merely updates an earlier document cannot stand on its own; it is
something that must be added to or inserted into the previously
existing document, and has limited usefulness independently. The
terms Supercedes and Replaces are no longer used.
Updates
To be used as a reference from a new item that cannot be used
alone (i.e., one that supplements a previous document), to refer
to the previous document. The newer publication is a part that
will supplement or be added on to the existing document; e.g., an
addendum, or separate, extra information that is to be added to
the original document.
Obsoletes
To be used to refer to an earlier document that is replaced by
this document. This document contains either revised information,
or else all of the same information plus some new information,
however extensive or brief that new information is; i.e., this
document can be used alone, without reference to the older
document.
For example:
On the Assigned Numbers RFCs the term Obsoletes should be used
since the new document actually incorporate new information
(however brief) into the text of existing information and is
more up-to-date than the older document, and hence, replaces it
and makes it Obsoletes.
In lists of RFCs or the RFC-Index (but not on the RFCs themselves)
the following may be used with early documents to point to later
documents.
Obsoleted-by
To be used to refer to the newer document(s) that replaces the
older document.
Updated-by
To be used to refer to the newer section(s) which are to be added
to the existing, still used, document.
我只发现了几个术语：
https://tools.ietf.org/html/rfc7322#section-4.1.4
4.1.4. Updates and Obsoletes
When an RFC obsoletes or updates a previously published RFC or RFCs,
this information is included in the document header. For example:
"Updates: nnnn" or "Updates: nnnn, ..., nnnn"
"Obsoletes: nnnn" or "Obsoletes: nnnn, ... , nnnn"
If the document updates or obsoletes more than one document, numbers
will be listed in ascending order.
https://tools.ietf.org/html/rfc7322#section-4.1
4.1. First-Page Header
Headers will follow the format described in "RFC Streams, Headers,
and Boilerplates" [RFC5741] and its successors. In addition, the
following conventions will apply.
RFC 7841 — header format for an RFCs "Relation to other RFCs"
...
[<RFC relation>:<RFC number[s]>] Some relations between RFCs in the
series are explicitly noted in the RFC header. For example, a new
RFC may update one or more earlier RFCs. Currently two
relationships are defined: "Updates" and "Obsoletes" [RFC7322].
Variants like "Obsoleted by" are also used (e.g, in [RFC5143]).
Other types of relationships may be defined by the RFC Editor and
may appear in future RFCs.