What are the little yellow lights next to the gamer tag in xbox live when i play halo 3?

You see when i'm playing Halo 3. during the game when i die it shows a list of the players in the game. And next to their gamer tags are little lights (yellow,green,red) what do they actually mean?|||thats their main armor color color and when they overlap two names that means they're in the same party|||I think it's like... scoring. Like, the people who have the most kills and stuff have green and the people with the least have red? I don't know, just guessing.