18- 127 C.M.R. ch. 158, § 2 - DEFINITIONS

ASCII - American Standard Code for Information Interchange. The de facto standard for code numbers used by computers to represent Latin letters, numbers and punctuation.

Assessor's Database - The database of property assessment information maintained by the assessor; it is also referred to as the tax list, property list, CAMA system, CAMA database, appraisal database etc.

Attribute - A single element of non-graphic (e.g., name of owner, property area, property value) information stored in a database field and usually, in the context of this standard, associated with a single geographic feature (e.g. a property parcel on a map).

Base Map - A map portraying basic reference features on the earth's surface (both natural and cultural) onto which other, specialized, features (e.g., property boundaries, water mains) are placed. A common example is a U.S. Geological Survey topographic map.

CAD - Computer Aided Design. Also sometimes called computer aided drafting, CAD systems assist in 2 and 3 dimensional engineering, architectural design and can be used for cartographic purposes.

Cadastral Map - A map showing the boundaries of the subdivisions of land for purposes of describing and recording ownership and taxation.

CAMA - Computer Assisted Mass Appraisal, an automated system for maintaining property data, valuing property, notifying owners, and ensuring tax equity through uniform valuations.

COGO - Coordinate geometry. A system for encoding and manipulating bearings, angles and distances from survey data into a digital system

Comma Delimited File- A flat ASCII text file in which the information such as the unique ID and field values are separated by a comma.

Digital Parcel File - A specific type of vector Spatial Data and is a representation of the boundary information originally depicted and maintained on a city or town assessor's maps. Besides fee ownership boundaries that may appear in this file or files, include public and private rights of way and various different kinds of easements. These files are typically created in and maintained using GIS software.

Digitizing - The process of converting features on a physical map into digital format. The x,y coordinates of the map features are recorded and stored as spatial data. Digitizing can be done manually on a digitizing tablet, on which the map is registered to a coordinate system and the features traced or by scanning the map and converting the image to vector data either with special software or by manual overtracing on screen.

Feature Attribute Table - A digital table, also known as an FAT, used to store the attributes of a specific feature class. The Feature Attribute Table is linked directly to a Spatial Data File. Examples are an ArcView shapefile Dbase table (.DBF), an Arc/Info Polygon Attribute Table (.PAT)

Parcel - The polygon representing the boundaries of legal ownership or interest on a city or town assessor's maps.

Polygon - A closed figure of three sides or more bounded by line strings intersecting at nodes.

Raster - A digital image file in which spatial data expressed as a matrix of discrete units called cells or pixels. Examples are an Arc/Info grid (cells) or a geotiff (pixels).

Registration - The process of finding reference points on a map or image document and assigning them coordinates from their known positions in the real-world. Once coordinates are specified for enough points on the map/image document, the entire digital document may be mathematically transformed to real-world coordinates for GIS display and analysis.

Related Database - An attribute table that can be temporarily associated with a Feature Attribute Table by making a connection between a record in the Feature Attribute Table and a corresponding record in the related attribute table.

Scan - The process of making a digital image of a document (e.g., a map, text document, or photo). A scanned document can be displayed on a computer screen, but until locations on the document are assigned ("registered") to map coordinates, it cannot be overlaid with map features in a GIS database.

Spatial Data - A digital file showing the location, shape of and relationships between geographic features. Spatial data can be in either vector or raster format. An example of a vector Spatial Data File would be a shape file. An example of a raster Spatial Data File would be a GeoTiff file.

Vector - A digital file in which geographic locations are represented by x and y coordinates. Points are located with a single x,y pair, lines defined by a series of x,y pairs and areas are defined by the line segments that enclose that area, or polygons.


18- 127 C.M.R. ch. 158, § 2

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