ROCKPORT — Finally it’s official: Biddeford High will play Class B football this fall.

“This is what we wanted for the kids,” said Biddeford principal Jeremie Sirois. “It will help level the playing field. Some of our rivalries will change.”

The decision came Thursday at the Maine Principals’ Association’s annual spring conference. The MPA’s general membership approved a measure that changes the waiting period for schools that apply up in classification from four years to two.

Biddeford had petitioned to drop from Class A to Class B but was turned down by the MPA in November. At that time a MPA rule stipulated that teams applying to play in a higher classification – as the Tigers had in 2012 – must remain in that class for four years.

But this winter the MPA’s classification and management committees decided to drop the waiting period to two years, in part because it makes it easier to track petitions through each two-year cycle.

The Tigers have won nine Class A titles since the playoffs were incorporated in 1967 – the most of any school – but none since 1994. Last season they were 4-6. The projected enrollment next fall is 775, which places the school among the Class B range of 586 to 839 students.

With anticipation that the measure would pass, the Tigers have planned their football schedule for the fall. Biddeford opens at Marshwood, the reigning Class B champion, and closes the regular season with Leavitt.

Sirois said the traditional Battle of the Bridge game with Thornton Academy is in “limbo.”

Several other measures were also approved by the MPA on Thursday:

 Cooperative teams will now be allowed in all sports. Currently, cooperative teams, in which athletes from two or more schools play as a combined team, are not allowed in sports in which a student can win an individual championship: track and field, swimming, golf, cross country, tennis, wrestling and skiing.

 Schools with 40 or fewer students of a gender will be allowed to use eighth-graders if necessary to fill out a team.

This change lowers the cutoff from 60 students of a gender. Schools are still not allowed to use eighth graders as a replacement for eligible athletes in grades 9-12.

 The Heal point formula was changed, reducing the preliminary point differential between classes from five to two.

This move was made to encourage crossover games between classes. For sports with three classes, wins against Class A opponents will still be worth 40 points toward a team’s preliminary point index, but Class B wins will now be worth 38 points and Class C wins will be worth 36 points. In sports with four classes, Class D wins will be worth 34. In basketball’s five-class format, the breakdown is: AA, 40; A, 38; B, 36; C, 34; and D, 32.

 Regions will go from East and West to North and South. As the statewide enrollment numbers have changed, the East/West line has moved south and this change reflects that.

 Because of a low number of teams, wrestling and Alpine skiing dropped from three classes to two.

In wrestling, Class A will be schools with enrollment of 575 or higher. In Alpine skiing, Class A will be schools of 500 students or more.