Final answer:
The category of frequency assignment authorization good for five years and entered into the Government Master File (GMF) is called an Exclusive Use License (EUL). This license grants exclusive access to a specific frequency band for a certain duration of time.
Step-by-step explanation:
The category of frequency assignment authorization that is good for five years and is entered into the Government Master File (GMF) is called an Exclusive Use License (EUL). This license is given to organizations or entities that require exclusive access to a frequency band for a specific period of time.
It allows them to have sole use of the frequency for their operations and prevents interference from other users. An example of a use case for an EUL is a television broadcasting station that needs a specific frequency band to transmit their signals without any interference.