(no subject)

It seems like it would be simple enough to simply add in an additional
header, so that clients and servers (and proxies) could phase in
support as they wish.

I guess the only real questions I have are:

  a) would anyone do it?
  b) is it too much of a `hack'?  The main advantage over simply
     changing the format of what gets sent to the server is that it's
     a smaller, simpler change and thus may be more likely to get
     implemented.

Opinions?