SHIRLEY -- Selectmen approved the final draft of a debt exclusion ballot question submitted for the Nov. 17 election. A district-wide election will determine if voters in Ayer and Shirley want the proposed $56.7-million high school renovation and addition to move forward.

A second election held concurrently that day will ask voters in Ayer and Shirley, respectively, if they will agree to a debt exclusion that would temporarily raise property taxes above the limits of Proposition 2 1/2 to help fund the building project.

The local cost of the high school project has been projected at about $19 million after state reimbursement, split between the two member towns via a formula in the regional agreement. But the ballot question won't include an amount for the debt exclusion.

"No dollar figure can be attached," Vice Chairman David Swain said. As explained at the recent special Town Meeting, the law won't allow it. Besides, there are variables, such as the interest rate when the School Committee goes out to borrow for the project and the term of the loan.

ASRSD Superintendent Carl Mock has said that the current "conservative estimate" for those two factors was four percent and 20 years, respectively.

Shirley's share of the debt service will vary over time, based on student enrollment.