Avidyne IFD540 Pilot's Manual page 25

Switching Between Com and Nav
To access the Nav frequencies for display or editing, push in the
lower left knob to toggle between Com frequencies and Nav
frequencies.
out back to com frequencies following 20 seconds of inactivity on
the Nav frequency display.
Invalid Frequency Entry Attempt
Attempting to type an invalid frequency (e.g. typing a nav freq in a
com slot) will produce a temporary error message indicating the
mistake. This message is unavailable in dual IFD installations
that have Keyboard Convenience mode (described later) turned
on.
Notification of Invalid Frequency Entry Attempt
COOL FEATURE
Shortcuts to Com Tuning
Shortcuts are provided to aid speed and ease of
manually entering a com frequency in the IFD. For
example, there is no need to type the leading "1" for
frequencies, the decimal point, trailing zeros or the
thousandth digit. For 121.700, type "217" and press
Enter.
System Overview
The displayed set of frequencies will always time
1-19