Above are examples of signs you will see on a run. Either in flour or marked with Chalk
Note you don't need to know any of the following but you might be interested before your first run.
Start of the run the runners/walker are shown the direction of the run. After a short period the first Mark will be found and the person finding it will shout "On On". Best to always shout "On On" when you see a marker to help people behind know which direction to go on. Only time not to shout "on On" is straight after a Check. Which is explained next.
At several points in a run you will find a Check . When found shout "Check!" . The first few runners start looking for the right route which could be in any direction.
It is the correct route if you find 3 Marks after the check e.g. three blobs of flour or chalk marks. At this point shout "On On" so everyone knows the right direction. The people at the Check can shout "On Back!" to the other runners Checking in other directions, so they know to return to the check as the correct route has been found.
Scrape a line from the center of the Check sign in the direction of the correct route. This will allow walkers/runners who have not got to the check yet to see which is the correct direction to go.
So the only time you don't shout "On On" when you see a Mark is for the first two Mark's you find when checking for the correct route after a check. Otherwise always shout when you see a marker.
Don't drive off after the run as this is a social event so wait around and join the hash circle when all the runners and walkers have arrived.