Lag Meter

in MW2 you can enable the Lag Meter Box type thing w/e you wanna call it and i was wondering if you could explain to me what the colors mean i know what the green color means but i wanna know whats the red line that jumps in randomly and the blue line going faster or slow or fast again what do those things mean

red line = if there is some lag the blue dont know

yellow = uhm well lets say if u have massive lagg

Red : Lagging VERY bad.
Orange/amber : OK/Still lagging
Green : Very good ping, but can still lagg a little bit.