Subject: If-Range and cache validation using Last-Modified

From: Matthew Cox <[email-masked]>
Date: Fri, 3 Jun 2011 16:16:22 +0000

Part 5 section 5.3 If-Range has the following text in the case that the response has no etag and only Last-Modified.
   If a client wishes to perform a sub-range retrieval on a value for
   which it has only a Last-Modified time and no opaque validator, it
   MAY do this only if the Last-Modified time is strong in the sense
   described in Section 2.1.2 of [Part4].

Section 2.1.2 in Part 4 has this text:
   o  The validator is about to be used by a client in an If-Modified-
      Since or If-Unmodified-Since header field, because the client has
      a cache entry for the associated representation, and

   o  That cache entry includes a Date value, which gives the time when
      the origin server sent the original response, and

   o  The presented Last-Modified time is at least 60 seconds before the
      Date value.

This seems to exclude If-Range which is strange since the If-Range text pointed to this section.  Is it possible to add If-Range to the text in the first bullet point, or make the text more generic such that it doesn't exclude other methods that use the Last-Modified time?

Thanks,

Matthew