The Workbench Slot
The Workbench slot is found in the middle of the screen between the Bus Racks. This can be used for previewing and cloning slots. You can drag and drop between itself and any slot in the rack.
It has all the same capabilities as any other slot, EXCEPT the output does NOT show up on any Buses or Screens.
For instance you drag a playing clip to it, adjust its FX stack while previewing the changes, then drop it back into the rack as a replacement or as new Slot.
It also has a special ability to use the Screen output as a source for experimenting with FX before showing them live.