What's "unknown request"?

Hello,

Please teach me about these cache.log messages.

ex1:
1999/11/18 11:30:39| internalStart: unknown request:
GET /squid-internal-static/icons/anthony-compressed.gif HTTP/1.0
Referer: ftp://ftp.datafellows.com/anti-virus/updates/avp
Connection: Keep-Alive
User-Agent: Mozilla/4.05 [ja] (Win95; I)
Pragma: no-cache
Host: ***.***.***.***:10080
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg image/png
Accept-Language: ja, en
Accept-Charset: Shift_JIS,*,utf-8
Cookie: SITESERVER=ID=6c1dea79fbac8d1778d0f2cf5081032e

What's "unknown request"?

Regards

--------------------------------------------------------------
Shunsuke Sato (sat@gn.ccc.canon.co.jp)
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Received on Wed Nov 17 1999 - 22:11:04 MST