What does the oven function "Supercook" mean?

All three elements are in use, which allows very fast preheating. This is an ideal function to use when sealing meat is required at the beginning of cooking — Fan Forced, Fan Assisted or Classic Convection may then be used to complete the cooking. For rare roast beef however, Supercook should be used for the entire cooking. Remember this function is all-round heat so used at lower temperatures gives beautiful, even cooking results.