usefor-article-13 May 2004

6.  Optional Headers

   None of the headers appearing in this section is required to appear
   in every article but some of them are required in certain types of
   article, such as followups. Any header defined in this (or any other)
   standard MUST NOT appear more than once in an article unless
   specifically stated otherwise.  Experimental headers (4.2.5.1) and
   headers defined by cooperating subnets are exempt from this
   requirement.  See section 8 "Duties of Various Agents" for the full
   picture.

--- ../usefor-article-12/Optional_Headers.out          November 2003
+++ ../usefor-article-13/Optional_Headers.out          May 2004