The event algorithm is as follows: 
Competitor’s ranking points
RP = A - B points, where
A = Competitor’s score/Winner’s score x 100 and
B = (Competitor’s time / Maximum time penalty) x (100 / Winner’s score)
Example:
A competitor has 17 controls correct with two timed controls = 55sec. The winner had 20 controls correct.
A = 17 / 20 x 100 = 85.0; B = 55/240 x 100/20 = 1.15; RP = 85 - 1.15 = 83.85 pts
For the Ranking list
The sum of the top 3 Ranking Points for the last 7 ranking events are divided by 3 to determine overall ranking. Apparent ties are resolved to the 4th decimal place. Trail O Event Directors and Course Setters receive a credit equal to their top result.
Key:
Para = Paralympic class
2012 Orienteering USA Trail O Rankings detailed (Excel spreadsheet; .xlsx)
2012 time control rankings ( for TempO)
Past years:
2011 Rankings reworked to remove ineligible persons.
