Filters peers based on Client ID. Client ID is exchanged at a later stage in a connection, but is the recommended way for client information (in an extensible human-readable format).
In this example:
Tixati version 2.xx
uTorrent/µTorrent x.x.x (any version)
Note: There's a client called "tTorrent" that identifies itself as "tTorrent v1.5.6" - due to mismatched character "v" the above pattern wouldn't capture it. But it may capture other similarly named clients.
DiscriminatedClient * (of any version or any ending)
Filters based on Peer ID. Peer ID consists partly of a simplified client type and version information and a randomly chosen identifier for this peer.
In this example (rules correspond to the ones above):
TIX02* (TIX is Tixati's ID and 02 is the beggining of the version string. Followed by random ID)
-UT* (-UT is a µTorrent ID followed by version number and random ID)
XYZ* (client which has the XYZ abbreviation code, followed by anything, likely version and random ID)