usefor-article-13 May 2004

5.7.  Injection-Date

   The Injection-Date-header contains the date and time that the article
   was injected into the network. Its purpose is to prevent the
   reinjection into the news stream of "stale" articles which have
   already expired by the time they arrive at some relaying or serving
   agent.

      header            =/ Injection-Date-header
      Injection-Date-header
              = "Injection-Date" ":" SP Injection-Date-content
                   *( ";" extension-parameter )
      Injection-Date-content
              = date-time

   See the remarks under the Date-header (5.1) regarding the syntax of a
   date-time and the requirements and recommendations to which it is
   subject.

   An Injection-Date-header MUST NOT be added to an article except by an
   injecting agent, hence it will never be present in a proto-article
   (8.2.1).  It MUST be added by each injecting agent but, once added,
   it MUST NOT subsequently be changed or removed by any other agent,
   even during reinjection (8.2.2).

        NOTE: The date-time would normally be expected to be later than
        the date-time in the Date-header, but differences between the
        clocks on the various agents and other special circumstances
        might vitiate that; no provision is made for any such
        discrepancy to be corrected - better that the injecting agent
        should just insert the correct time as it sees it.

        Since this header is newly introduced in this standard, other
        agents cannot rely on its always being present; therefore,
        provision is made (8.3,8.4) for the Date-header to be used when
        it is absent.

   This header is intended to replace the currently-used but nowhere-
   documented header "NNTP-Posting-Date", whose use is now deprecated.