It would be a great addition to have a separate button or at least an optional function on some button (like you can switch the Apply/Copy to Stationery functions) to check/uncheck all IPTC fields but opposed to Clear all their content would stay in tact just the checkmarks would be affected allowing the user to choose which ones to reactivate/deactivate depending on he/she needs many of them but not all, or some of them.
I could also imagine an option to save a "mask" telling which fields to activate/deactivate if a masking button is clicked. But the check/uncheck all button would be a great time saver.
