What does 'Freeze Frame' data mean and when is it stored?

Freeze Frame data is a snapshot of engine and emissions system conditions recorded at the moment a Diagnostic Trouble Code caused the Malfunction Indicator Lamp (MIL) to turn on. It includes information such as fuel system status, engine load, coolant temperature, fuel trim value, MAP vacuum, engine RPM, and DTC priority. This data is always associated with the highest priority code (Code #1) and is also erased when the ERASE function is used. (Page 37)