questions concerning about the range requests

hi, folks,
I found that the range requests(requests with Range specified at the head)
are partially supported.
What partially I mean here is that: follow the code, it seems
the request could be processed by squid, but the reply for this
kind of requests will not be saved to the local disk. (In
httpCachableReply, the PARTIAL_CONTENT status will not be swappable.)

So my questions about this are: what prevents from saving the partial
content to the disk? what if the PARTIAL_CONTENT turns to be swappable?

Is that the potential "fake hit" for the later
requests since range is has nothing to do with the MD5 key? If it is,
I think the content may be checked from the cached data to find it is not
a REAL hit and seems not very hard to do.
And I also want to know the future plan of processing range requests.

Thank you.

-- 
Chen,Songqing
Dept. of Computer Science
College of William&Mary