The game award system is based on US Army, US Navy, and US Marine Corps awards.
There are totally 25 awards exist. Most of them increasingly awarded on the basis of recipient's valor in battle. A part of them (e.g. Purple heart, for being wounded in combat) are out of this order and awarded on special events.
Most of awards can be decorated several times. Each next one is designated with single bronze oak leaf upon ribbon. A silver oak leaf is substitutes for five bronze leaves. Hence, a ribbon with a silver oak leaf means six sequential decorations of the current award.