What's the safest way to clean the microwave oven?

Be sure to unplug the appliance from the power supply first. Clean the cavity with a slightly damp cloth after each use, and carefully clean the door frame and seal with a damp cloth when dirty. For easier cleaning, you can place half a lemon in a bowl with 300ml water and heat on 100% microwave power for 10 minutes, then wipe clean with a soft, dry cloth. Do not use harsh abrasive cleaners or sharp metal scrapers as they can scratch the door glass. (Page 8)