Just found this from WW2OL page.
I know you can find this yourself, but as it is so close to this thread...
" Our icon system is a combination of old tried and true methods and some cool new stuff.
Icons are displayed for the following:
1) All aircraft: Game IDs on friendlies, and plane types on enemies.
2) Friendly troops and ground vehicles. Enemy troops and GVs do NOT display any icons.
The basic display shows Icons (as described above) in a unique way. They fade in with time-in-view. This gives a feeling of having to really "look" for them. Quick view panning gives little or no icon feedback, while longer times in a single view will start to fade in Icons within that FOV, switch to another and you’ll have to wait a tad for these new ones to fade in. Distance is also factored into display, so as you get closer the icon fades in as well. These two paradigms combine for a great icon effect. You really get the feeling of distance and time in view. As well, the time off target is a fade out, so you get a very cool effect while scanning:
Say you look left to a tree line…as you hold your view there a few friendly troop icons fade in. You hold a bit in that view until they are fully developed, game IDs fade in and you know who’s “with you”. Switching to straight ahead now, you see 3 tanks in the distance, firing. As you hold sight on them, 2 icons fade in, showing you that one of the tanks is an enemy. You look left again, and your troops icons are still there, but have faded a touch depending on how long you were watching the AFVs slug it out. This works fantastically for air to air fighting. “Loose sight, loose the fight” never was so true in a flight sim.
Aircraft have a very cool closure indicator that I won't explain fully right now, but it dynamically changes the shape and area of the icon as closure rates shift. It gives you positive closure feedback at all distances, and it is not linear, meaning the faster the closure rate the more dynamic the icon’s transformation."