The Planning Board on Monday is continuing its series of public hearings on proposed zoning bylaw changes. The town’s Zoning Advisory Committee has been working since 2008 to draft amendments to the bylaws in such categories as open space protection, commercial development, and zoning subdivisions. The proposal will be brought before the town this fall at a Special Town Meeting. A particularly hot-button issue at the last Planning Board forum was the proposed regulation of open space residential development, which would give developers some leeway on density limits in exchange for indefinitely preserving 50 percent of the parcel as open space. Monday’s hearing is set to convene at 7:30 p.m. in the Town House, 17 Common St.