I have an electrical device which I want to test when it is turned off (no power supply to the device). I am writing a test for this and need to state that the device shall be turned off during the test.
Which of the following is/are correct:
-Operation mode: Power off
-Operating mode: Power off
-Operational mode: Power off
Provided you are consistent throughout your document, you could get away with all of those. If the device has a handbook, you should copy whatever version it uses.
If it doesn't, then I would recommend this order:
-Operating mode: Power off (< best version)
-Operation mode: Power off (< fair version)
-Operational mode: Power off (< works but best avoided)