How does the radar in Crysis work?

Maximum zoom is x6.Untaged enemies are indicated as green and after you tag them it turns red and they appear on the radar.Now, for the alertness meter:The bar at the left shows if and how well an enemy unit has visual contact with you.The more it raises the more clear you become to the enemy's eyes.If it reaches maximum then the enemy has direct visual contact with you and starts shooting you.The caution symbol indicates if the enemies know you are somewhere close (it turns bigger and red if the enemies know you're around there and become cautious but this doesn't mean that they also have a visual on you so that the alertness meter increases).