Panasonic CF-29 Series Reference Manual page 11

LED Indicators
Power status of the
*1 multimedia pocket
This indicator lights when power is supplied to a device in the multimedia
pocket.
It is not lit when a second battery pack is installed in the multimedia
pocket.
You can confirm the status of the second battery pack with
(multimedia pocket device status).
*1
MP is the abbreviation for Multimedia Pocket.
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