Cirrus DESIGN SR22 Pilot Operating Handbook page 440

Section 9
Supplements
When the above conditions have existed for 10 seconds, the GS
annunciation will illuminate indicating GS arming has occurred (ALT
annunciation will remain on). When the glideslope is intercepted and
captured, the ALT annunciation will go out.
REV- Reverse Course Button
When REV is selected, the autopilot will automatically execute high
sensitivity gain for an approach where tracking the front course
outbound or tracking the back course inbound is required. The APR
and REV annunciations will illuminate when REV is selected.
TRIM - Autotrim Mode
When both a roll mode and a pitch mode are engaged, the autopilot
will provide an annunciation whenever it is automatically trimming the
aircraft. Should the pitch servo loading exceed a preset threshold for a
period of three seconds, the autopilot will annunciate either TRIM  or
TRIM  as an advisement that the autopilot is automatically trimming
the aircraft. If the autopilot is still in the process of automatically
trimming the aircraft after four more seconds, the annunciation will
flash. When the aircraft has been sufficiently trimmed, the
annunciation will extinguish.
VS Modifier Knob
The VS Knob on the Programmer/Computer is used to change the
vertical speed when in vertical speed mode and controls altitude
reference when in altitude hold mode. Each 'click' of the knob results
in a step increase or decrease in the selected mode by the amount
shown in the table below.
Mode
Altitude Hold (ALT)
Vertical speed (VS)
* Adjustments greater than 360 feet can be made by selecting VS mode and flying
the airplane to the new altitude and then re-engaging ALT mode
18 of 24
Step Value
20 Feet
100 Feet per Minute
Cirrus Design
SR22 / SR22T
Range
+/- 360 Feet*
+/- 1600 Feet per Minute
P/N 13772-140
Revision 02: 09-20-12