Playing recently in Colin McRae: Dirt 2 and Dirt 3 I was curios about co-pilot commands.
After a small research I found that this is what called Pacenotes. It's coded language for drivers and their co-pilots for describing a route in extreme details. It can look like hieroglyphics "MC1 100 KL2 100 KR2 200 SQL" but it is a lot of information coded here.
Simple calls:For turns naming, there is colored map
Easy left/right: An easy, usually flat out corner.
Medium left/right: A tighter corner, a tap of the brake usually needed.
Hard left/right: A tight corner with a lot of brake needed.
Hairpin left/right: A very tight corner that turns in on itself, often turning 180 to go back alongside the road you entered the corner on. For these its best to brake hard before tapping the hand brake to slide to the exit.
90 left/right: A tight, right angled corner
1 left/right: A very tight corner, almost a hairpin.
6 left/right: A very easy, almost imperceptible corner.
Hairpin is the same.
Some nice videos
What do the co-driver calls mean in Dirt 2?
WRC - Team talk: Pace notes explained
Co-driver language for calling turns?
Jemba Inertia Notes System