Each zoning district is designated by a letter indicating the general land use classification – R for Residence, C for Commercial and M for Manufacturing – followed by one or two numbers and, sometimes, a letter suffix. In residence districts, generally, the higher the first number, the greater the density permitted and the larger the building. Parking requirements usually decrease as density increases. A second number, following a hyphen (such as R3-1 or R3-2), denotes variations in use, bulk or parking regulations among districts within a common density category. In commercial and manufacturing districts, the first number denotes the intensity of permitted uses; the higher the first number, generally, the broader the scope of uses that are permitted and the more significant the land use impact of such uses. The second number, following a hyphen, denotes differences in bulk or parking regulations within a common use category. The higher the second number, generally, the larger the building permitted and/or the lower the parking requirements. Letter suffixes have been added to the designations of certain districts (such as R10A) to indicate contextual counterparts that seek to maintain, enhance or establish new neighborhood characteristics or building scale.