Avidyne IFD540 Pilot's Manual page 126

Setting up customizable datablocks is accomplished using the
"Datablock" LSK on the SETUP tab of the AUX page and
selecting "Setup" as the option.
Once on the Datablock Setup page, use the bottom right IFD
knob in the following manner:
Outer Ring
Inner Ring
Datablock Setup
Any change made on this page is immediately accepted with no
special "save" step required. Datablocks can be inserted along
the upper left edge of the display, along the top edge of the
display and along the entire right edge of the display.
As you twist the outer ring of the bottom right IFD knob while on
the Datablock Setup page, you will notice a blue filled box that will
jump from one datablock slot to the next.
4-18 AUX Pages
Selects the desired page location (middle of top
strip in the example below)
Selects the data item from the list (GPS AGL
Altitude in the example below)