Cessna TURBO CENTURION T210M 1978 Pilot Operating Handbook page 324

CESSNA 800 ALTITUDE PILOT'S OPERATING HANDBOOK
ENCODING/ ALERTING/PRESELECT SUPPPLEMENT
in the altitude hold mode but the green CPLD lamp will go out to
indicate that the altitude displayed is not the altitude at which the
airplane is being held.
4. If the altitude hold is manually selected on the flight director mode
selector prior to automatic altitude capture, the ARMD lamp will
go out, the CPLD lamp will not light, and the capture logic circuits
will have to be reset for the next use. The function may be reset
after altitude hold is disengaged.
SECTION 5
PERFORMANCE
There is no change to the airplane performance when this avionic
equipment is installed.
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