This post is part of an Enduro series you can start your reading here
What is an Enduro? What you need to ride an Enduro
Basic Enduro Rules
Key Time - The scheduled starting time and scheduled time of arrival at each checkpoint for a rider on row OO. (Row Zero)
Free Zone – Timed checkpoints, including Known Controls, cannot be located closer than 3 ground miles apart. Therefore 3 ground miles before, or 3 ground miles after a timed checkpoint can be considered "Free Zones". Similar Free Zones may apply to Gas Stops, usually with timed checks no closer than 2 miles before, or 3 miles after the Gas stop. A "Free Zone" is a distance on the race course where no checkpoints are possible.
Reset – A point along the course where the posted Mileage is advanced to some greater number. This gives a rider on schedule a rest period of the period of time it would have taken the rider to ride the mileage advanced.
Free Time – A point along the course where the Mileage remains fixed while the time is allowed to run. A rider on schedule would wait until the Free Time has run out, then he would proceed down the course. It has an effect very similar to a Reset.
Ground Mileage – The actual Mileage traveled by a rider, which is the posted Mileage minus any Resets.
Checkpoints
Checkpoints are located along the course where crews will mark the minute, and seconds if an Emergency check, that a rider enters the check. The Key Time and the Mileage for that check should be posted near the flags. The Mileage accuracy for the check location must be within 1 tenth of a mile, while the clocks used at the check must be within 10 seconds of the master Key Clock. The colors of the flags used to mark each check are shown in parenthesis.
Secret – (Red & White) An unknown, timed checkpoint.
Emergency – (Green & White) Same as a Secret check, except the minutes and seconds are recorded.
Known Control – (Yellow) A timed checkpoint whose location is known to all participants.
Observation – (White) An unknown, un-timed checkpoint where no time penalty is recorded.
Scoring
After the race, penalty points are computed based on the rider’s variance from a perfect schedule.
All checks
EARLY: More than 15 minutes – disqualified from that point.
LATE: More than 60 minutes and 59 seconds – disqualified from that point.
Secret
EARLY: 2 points for the first minute, plus 5 points for each additional minute
LATE: 1 point for each minute.
Emergency
The major points are computed like a Secret check, with Tie-breakers points placed after the major points.
Tie-breaker points are the total number of seconds from the 30 second point of the rider’s due minute.
Known
EARLY: Zero points for early up to 15 minutes, 2 points for each minute for an early departure.
LATE: 1 point for each minute.
From
ico racing website