The Planning Board on Sept. 9 will continue its hearing on whether to impose a moratorium on medical marijuana centers while planners study zoning changes to comply with state law. The board is considering a zoning bylaw to limit these centers to certain parts of town, in compliance with Department of Public Health guidelines. While no one has approached the town about opening a treatment center, one could open anywhere in town if a zoning bylaw isn't in place, said Town Planner Tom Bott. A moratorium on treatment centers would require Town Meeting approval. The town often holds a Special Town Meeting in October, but one hasn’t been called so far this year. The next annual Town Meeting is in the spring.