HTTP reply code 304 and access type TCP_MISS

What does the combination of HTTP reply code 304 and access log type
TCP_MISS mean? I found that most of my access log lines which show return
code 304 are of access type TCP_MISS. 304 also occurs with
TCP_CLIENT_REFRESH, TCP_IMS_HIT, TCP_IMS_MISS.

The access log is from Squid 1.1.5.

Thanks,
Carlos
Received on Sun Feb 23 1997 - 14:52:15 MST