can't read "x": no such variable
I'm using XOTcl 1.0.2 (compiled from source) & Tcl 8.4.2 (.deb) on Linux.
I had the same issue when I was experimenting with binding sql results into different variable names using traces. However, I haven't checked it out further but I suppose it could be handled by the unknown mechanism.
(Neophytos: yes, I am the author of nstcl fame, though I didn't realize that would make me famous anywhere. :-)
:) Still it is nice to see that you are considering xotcl ...
Best wishes, Neophytos