Rule of 13

This guideline or rule applies when you are considering opening a strong hand with artificial 2 opening bid, when the cards do not exceed the 22 honors HP and the doubt is whether to open at the 1 level on a long suit or an artificial 2.

   The concept is based on adding the total number of defensive tricks and multiply by two.

   The defensive tricks are determined according to:

A:	1
A/K:	2
K/Q:	1
K/x:	1/2
Q/J/x:	1/2

Once the number is calculated, the player must add the amount of cards in all suits of more than 3 cards … If the result is 13 or more, the player must open 2.