rfc - RFC 中的 "obsoletes"和 "updates"有什么区别？

Question

rfc-editor说

• "Obsoletes xxxx" refers to other RFCs that this one replaces.
• "Updates xxxx" refers to other RFCs that this one merely updates but does not replace.

但这引出了一个问题……为什么一个 RFC 会更新另一个 RFC 而不替换它？

“更新”是否意味着一些较早的信息与旧的 RFC 相矛盾，但其他信息仍然是标准的？这似乎很奇怪。

Answer 1

条款 更新 和 过时 过去由 RFC 2223 定义，但它已被 RFC 7322 废弃，它没有明确定义这些术语。
我认为早期的 RFC 在定义这些术语方面做得很好。
RFC 2223 — 过时:1543 , 1111 , 825
RFC 2223、1543 和 1111 都是必不可少的“RFC 作者说明”，将这些术语定义为“与其他 RFC 的关系”。 RFC 825 是一个非常早期的版本，并没有定义这些术语。

RFC 2223 — 6. Relation to other RFCs

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.

RFC 7322 — 过时: 2223
RFC 7322 没有像早期的 RFC 那样定义 RFC“与其他 RFC 的关系”。
我只找到了几个术语的提及:

https://www.rfc-editor.org/rfc/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://www.rfc-editor.org/rfc/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 5741被提及，已被 RFC 7841 废弃.它描述了 RFC“与其他 RFC 的关系”的 header 格式，但它只是指回 RFC 7322 .

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.