Hi Dan,

The best place to ask these questions is on the development mailing lists, dev@core.limewire.org or dev@gui.limewire.org .

In a nutshell, X-Guess advertises support for UDP querying, X-Version advertises the most recent LimeWire version, X-Ext-Probes advertises support for probe queries, and X-Degree advertises how many ultrapeers you intend to connect to.