Iconoclast -- RPG -- Cover
Cover is anything being used as armor that is not being worn or carried by you. Other than that, it is dealt with in the same exact way as armor. Just like armor, all cover has both a Durability Value (which determines how much damage it can stop), and a Trauma Capacity (which determines how many holes you can punch in it before it falls apart). Hard cover merely has a higher Durability Value than soft cover; bushes absorb little, walls a lot.
When standing behind cover, you also reduce your chance to be hit by a percentage equal to the percent of you that's covered by the cover. If you're 50% concealed by a wall, there's a -50% chance to hit you.
Of course, if an opponent is using targeted shots, cover is ignored if they aim at a part of your body that is not concealed. Thus, if you stand behind a brick wall with only your head showing, they can take a -20 percent to aim at your head, instead of the -90 percent chance to hit you in general. Remember to keep that head down.