From the Tcl man page for [uplevel]:
"The uplevel command causes the invoking procedure to disappear from  
the procedure calling stack while the command is being executed. In  
the above example, suppose c invokes the command
uplevel 1 {set x 43; d}
where d is another Tcl procedure. The set command will modify the  
variable x in b's context, and d will execute at level 3, as if  
called from b. If it in turn executes the command
uplevel {set x 42}
then the set command will modify the same variable x in b's context:  
the procedure c does not appear to be on the call stack when d is  
executing. The command ``info level'' may be used to obtain the level  
of the current procedure."
This is very devious and will require some more tests (and  
implementation) for ParTcl (once [uplevel] works at all).
--
Matt Diephouse