What does TCP_REFRESH_HIT resp. TCP_REFRESH_MISS mean?

While analysing the access.log-files of squid 1.1.betaxx I often found
the codes TCP_REFRESH_HIT and TCP_REFRESH_MISS. I think I do know what a
TCP_REFRESH is, but I do not know the exact meaning of a TCP_REFRESH_HIT
and TCP_REFRESH_MISS. I thought a TCP_REFRESH occurs if a user forced a
refresh ("reload"). Then the "Pragma: no-cache" header is sent by the
client. So when do I get a HIT or a MISS and what does squid do in both
cases?
                                               
Then I found out that squid often got the same object twice. The first
time DIRECT and the second time via a PARENT_HIT.

848359095.145 577 193.174.75.154 TCP_REFRESH_HIT/304 65 GET
http://www.vox.de/heute1.gif - DIRECT/www.vox.de
848359095.150 695 193.174.75.158 TCP_REFRESH_HIT/304 65 GET
http://www.vox.de/heute1.gif - PARENT_HIT/karlsruhe.www-cache.dfn.de

Is this intended or does it just happen when the time between both replies
is too short? Besides, why are the caches involved in this request, though
the "Pragma: no-cache" header is sent by the client?
  
Thank you

Joern

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E-Mail: 	jacha@rvs.uni-hannover.de