          global varname ?varname ...?
               This command is ignored unless a Tcl procedure is being
               interpreted.    If  so,  then  it  declares  the  given
               varname's to be  global  variables  rather  than  local
               ones.   For  the duration of the current procedure (and
               only while executing in  the  current  procedure),  any
               reference  to  any  of  the varnames will be bound to a
               global variable instead of a local one.
