Access Log Types:

"TCP_" refers to requests on the HTTP port (3128)

    TCP_HIT
	A valid copy of the requested object was in the cache.

    TCP_MISS
	The requested object was not in the cache.

    TCP_EXPIRED_HIT
	An expired copy of the requested object was in the cache.
	Squid made an If-Modified-Since request and the response was
	"Not Modified."

    TCP_EXP_FAIL_HIT
	An expired copy of the requested object was in the cache.
	Squid attempted to make an If-Modified-Since request, but it
	failed.  The old (stale) object was delivered to the client.

    TCP_EXPIRED_MISS
	An expired copy of the requested object was in the cache.
	Squid made an If-Modified-Since request and received a new,
	different object.

    TCP_REFRESH
	The user forced a refresh ("reload").

    TCP_IMS_HIT
	An If-Modified-Since GET request was received from the client.
	A valid copy of the object existed in the cache.

    TCP_IMS_MISS
	An If-Modified-Since GET request was received from the client.
	The requested object was not in the cache.

    TCP_SWAPFAIL
	The object was believed to be in the cache, but could not be
	accessed.

    TCP_DENIED
	Access was denied for this request.


"UDP_" refers to requests on the ICP port (3130)

    UDP_HIT
	A valid copy of the requested object was in the cache.

    UDP_HIT_OBJ
	Same as UDP_HIT, but the object data was small enough to be
	sent in the UDP reply packet.  Saves the following TCP
	request.

    UDP_MISS
	The requested object was not in the cache.

    UDP_DENIED
	Access was denied for this request.

    UDP_INVALID
	An invalid request was received.

    UDP_RELOADING
	When the cache is reloading the store metadata, it may be
	desirable to have clients only fetch HIT's from your cache.
	This opcode means "I am alive, but please don't request this
	object from me."
