Definitions:


ATTRIBUTE: Overhead
Data description, characteristic or quality. Describes or explains the data. For example, “Vegetation = brush, 10 ha, and owned by Mrs. Jones” contains three attributes: identification, size, and ownership.

GIS Overhead
Geographic Information System: A computer-based system that enters, stores, manages, analyzes, and presents spatial (and associated non spatial) data, combining databases and graphics operations to make a variety of products from lists to maps.


QUERY
Asking a question of a database, typically in the form of a command for specific data.


RASTER- Overhead-1 Overhead-2; Overhead-3
A cell that contains a single GIS value. The cell is part of a larger grid system (rows and columns) constituting an entire coverage. A raster GIS system uses a data structure that uses a grid system.


RELATIONAL DATABASE
- Overhead-1; Overhead-2; Overhead 3
A powerful and flexible type of database that allows multiple linkages of data so that each field can be related to all other fields. Typically a relational query consists of defining specific conditions from one or more fields to find records meeting all or many of those needed conditions. For example: Find (1) all properties valued over $50,000 AND (2) that are used for farming AND (3) that cover over 50 acres.


SPATIAL DATA
Overhead-1; Overhead-2
Data that occupies cartographic (mappable) space and usually has specific location according to some georeference system (such as Latitude-Longitude). In a GIS, may be associated with non spatial data. For example, the location of a political area is spatial, as is its area: the name and demographics are non-spatial. Also known as geographic data.


VECTOR Overhead-1; Overhead-2
Refers in GIS to a data structure that defines points, lines and polygons by their true position and dimensions. Each point on a chain (node) is a coordinate label rather than a graphic item. For example, a square is defined by the coordinates of all four corners rather than by four drawn lines. This allows high accuracy at any scale and is more “maplike” than a raster system