Two alternatives relating to medical marijuana dispensaries are among the key items coming to fall Town Meeting, which convenes Tuesday at 7 p.m. at the middle school. One calls for the adoption of a zoning bylaw that would allow medical marijuana dispensaries in industrial districts only, with a special permit. The facilities would have to be at least 500 feet from schools, parks, and other specified facilities. The other proposal would extend until June 30, 2014, the existing moratorium on dispensaries that is set to expire in late November. A related article proposes to ban the possession, consumption, or sale of synthetic marijuana. The meeting will consider a number of spending requests, and amending the bylaw that allows the keeping of one fowl per 2,500 square feet in residential areas, to exclude roosters, peacocks, and guinea hens.