Mil Std 2525C which sets the standard for all of those little pictures situated on your map overlay was updated over a year ago and one of the most significant, yet overlooked changes was the addition of map symbology for IEDs.
The Army is making a major push to integrate the new icons into digital C4ISR systems so you should be begin to see them soon on a FBCB2 screen near you. For those of you who would like a guide to learn to decipher all of those diamonds and rectangles, check out Mil Std 2525C.