As best I can tell, only one icon (arrow/triangle) is currently used for all types of traffic. The GDL90 data specification has a bunch of diffferent Emitter Categories that can be sent. It would be nice to be able to choose different icons for traffic based on the Emitter Category.
Specifically, I'm kicking around the idea of converting received marine VHF AIS data to GDL90 format and sending it to the app so that marine vessel locations would show up on the map as "traffic". It would be nice to be able to quickly visually differentiate these (using a GDL90 Emitter Category of "Surface Vehicle") at a glance beyond the relative altitude number.