hi,
this is just a limewire proposal and as far as i know it isn't used beacause all these things can be done with the 0.6 handshake.


here some lines (0.6 specification):
.......
Lime Wire LLC had proposed using the GUIDs of initial ping requests as
a form of protocol versioning. For example, the last byte of the GUID
of the first message by a client would be 0 if the client spoke the
"Gnutella 0.5" protocol, 1 if the client spoke the "Gnutella 0.6"
protocol, etc. While this scheme is backwards- compatible, it is
imperfect. First, it does not provide ways for clients to support
different combinations of protocol extensions. If, for example,
clients at the "0.6" level were to support QRP and pong-caching, a
servent would be required to implement both. Second, this scheme
places a burden on the servent implementer. For example, a servent
trying to accept only connections with QRP support must put new
connections on "probation" until it has received the initial ping.
.......

CU