Each team scores points based on the results of their matches.
Each team's rating is equal to its total points scored divided by the total matches played. (Series are not significant in these calculations).
A match only counts if played in the last three years.
Matches played in the first year of the three-year limit count one-third; matches played in the second year count two-thirds; matches played in the last year count fully; essentially, recent matches are given higher weighting.
To determine a team's rating after a particular match:
Determine the match result (win, loss, or tie)
Calculate the match points scored:
If the gap between the ratings of the two teams at the commencement of the match is fewer than 40 points, then:
The winner scores 50 points more than the opponent's rating
The loser scores 50 points fewer than the opponent's rating
Each team in a tie scores the opponent's rating
If the gap between the ratings of the two teams at the commencement of the match is more than or equal to 40 points, then :
The winner, if it is the stronger team, scores 10 points more than its own rating
The winner, if it is the weaker team, scores 90 points more than its own rating
The loser, if it is the stronger team, scores 90 points fewer than its own rating
The loser, if it is the weaker team, scores 10 points fewer than its own rating
The stronger team in a tie scores 40 points fewer than its own rating
The weaker team in a tie scores 40 points more than its own rating
Add the match points scored to the points already scored (in previous matches as reflected by the Table) and determine the new rating. However, matches(and the points) which do not lie in last three year range will have to be removed.
Points earned by teams depend on the opponents ratings, therefore this system needed to assign base ratings to teams when it started.