In general, only objects and barrels, because most of the enemies and civilians are constantly moving, making difficult to establish a place of their initial position. Well, except that at level 4 "Park" designated civilian as they are all fixed.
At first, I wanted to mark stationary enemies, but then decided that it would only confuse and clutter the map. Maybe then when better study the technology for mapping.
But you have the right to make your map as you wish