multipart/byteranges minimum number of parts

Hi!

The spec contradicts itself regarding the minimum number of parts in a 
multipart/byteranges response: On the one hand, "A response to a request 
for multiple ranges, whose result is a single range, MAY be sent as a 
multipart/byteranges media type with one part", while on the other hand, 
"The multipart/byteranges media type includes two or more parts". If a 
multipart/byteranges media type indeed must include two or more parts, 
the first statement makes for an illegal response. And if a one-part 
response is valid, then the second statement is incorrect.

Since the spec also mandates that a client requesting a single range 
must never receive a multipart/byteranges response, it seems like the 
intention was to make it possible for a client to support partial 
retrieval without having to implement multipart support at all, in which 
case it would have been more straightforward if the spec simply required 
all single-range responses to use Content-Range and not 
multipart/byteranges. For backwards compatibility,  it can 
encourage/require multipart/byteranges recipients to properly handle 
single-part messages as well, which is very likely the case in existing 
implementations.

In any case, this contradiction should be fixed and the use cases clarified.

Thanks!

Amichai