JVC KD-SX855R Instruction Manual page 11

Mode 1 (AF:on / REG:off)
Network-Tracking is activated with Regionalization set to "off."
Switches to another station within the same network when the receiving
signals from the current station become weak.
Note:
In this mode, the programme may differ from the one currently received.
Mode 2 (AF:on / REG:on)
Network-Tracking is activated with Regionalization set to "on."
Switches to another station, within the same network, broadcasting the same
programme when the receiving signals from the current station become weak.
Mode 3 (AF:off / REG:off)
Network-Tracking is deactivated.
The same programme can be received on different frequencies.
Programme 1 broadcasting
on frequency A
Programme 1 broadcasting on
frequency B
Programme 1 broadcasting on frequency C
Programme 1 broadcasting on frequency E
Programme 1 broadcasting on frequency D
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