Show field code in the data monitor
The field code for the currently-active field always shows in the blue bar at bottom left of the TaxCycle windows. (Click on this also copies it to your clipboard.)
If you prefer, you can add a data monitor to show the current field code. Right, click on a cell in the data monitor and select Show field code. Unlike the link in the blue bar at the bottom of the window, clicking on the data monitor cell when showing the current field code does nothing. It does not copy it to your clipboard and it does not take you to the related field.