Just looking at the server disassembly, I can tell you the parameters are base nickname, player number and base test (if (test) if (base_arg != player[iBaseID]) return;). It's only explicitly called once in server.dll, at IServerImpl::DisConnect, where test is false. It's not explicitly called in freelancer.exe, common.dll or content.dll (according to my listings) but there may still be virtual calls (need to debug to test that).