some questions

[Alexey Toptygin]

I cen't seen to find where the all the parameter expansion types for 
string capabilities are documented. Can anyone point me to it?

Also, what are the userX capabilities? They seem to be defined quite 
frequently, but what do they do?

Finally, is there a standard capability name for i.e. setting the xterm 
window title with "\E]0;newtitle^G"?

                        Alexey