s.

<li><b>Enable the $tkg$recv() and $tkg$send() system tasks:</b> If
enabled, user circuits can use the $tkg$recv() and $tkg$send() system
tasks.  These are necessary for VPDs (Virtual Peripheral Devices) to
work properly.

<li><b>The $tkg$exec() system task is:</b> The $tkg$exec() system
tasks allows a user to execute an arbitrary Tcl/Tk command in the
context of TkGate. Indirectly this could cause an arbitrary shell
command to be executed.  Some VPD implementations use this mechanism
to pass data betwee