If you google around you can find various discussions on this. One link suggests that such data was promised but not delivered. I suspect Mr Monroy could not get hold of the document specs from Avidyne and did not want to put in the (significant) effort to reverse engineer the symbol definition and placement data stream
What puzzles me is how they can get 1090MHz
azimuth data using the single external antenna shown on page 4
here, which has only a single BNC connector.
They claim to display only quadrants but even so I can't see how it can work.