K
key attributes
To join two tables together, each table must have a column containing the same values. For example, a country feature with a "Name" attribute can be joined to the appropriate record in a table of demographic data that has a "Country_Name" column. See also relate, relationship class, primary key, and foreign key.
Kriging
A geostatistical interpolation method based on statistical models that include autocorrelation (the statistical relationship among the measured points). Kriging weights the surrounding measured values to derive a prediction for an unmeasured location. Weights are based on the distance between the measured points, the prediction locations, and the overall spatial arrangement among the measured points.

L
label
Text on a map that provides map readers with additional information about a feature. ArcMap can label features on the fly with any of their attributes (or with text from several fields) and has advanced options for label placement and visibility. Labels can be made into annotation layers and then stored in geodatabases.
label point
A feature class in a coverage used to represent point features and identify polygons.
lag
The line (vector) that separates any two locations. A lag has length (distance) and direction (orientation).
LAN
Local area network. A computer data communications technology that connects computers at the same site-for example, all computers in the same building. Computers and terminals on a LAN can freely share data and peripheral devices such as printers and plotters. LANs are composed of cabling and special data communications hardware and software. See also WAN.
latitude
The angular distance (usually measured in degrees) north or south of the equator. Lines of latitude are also referred to as parallels. See also geocentric latitude and geodetic latitude.
latitude of center
The latitude value that defines the center (and sometimes origin) of a projection.
latitude of origin
The latitude value that defines the origin of the y-coordinate values for a projection.
latitude—longitude
A spherical reference system used to measure locations on the earth's surface. Latitude and longitude are angles measured from the earth's center to locations on the earth's surface. Latitude measures angles in a north-south direction. Longitude measures angles in an east–west direction.
layer
A collection of similar geographic features—such as rivers, lakes, counties, or cities—in a particular area or place referenced together for display on a map. A layer references geographic data stored in a data source, such as a coverage, and defines how to display it. You can create and manage layers as you would any other type of data in your database.
A feature class in a shared geodatabase managed with SDE 3.
layout
The design or arrangement of elements—such as geographic data, North arrows, legends, and scale bars—on a digital map display or printed map.
layout view
The view for laying out your map in ArcMap. Layout view shows the virtual page upon which you place and arrange geographic data and map elements—such as titles, legends, and scale bars—for printing. See also data view.
least-cost path
See shortest path.
left-right topology
The topological data structure ArcInfo uses to represent contiguity between polygons. Left-right topology supports analysis functions such as adjacency. See also topology.
legend
A list of symbols appearing on the map; includes a sample of each symbol and text describing which feature each symbol represents.
library
A collection of spatially related ArcStorm or Map LIBRARIAN layers. A library has a spatial extent that applies to all layers in the library.
linear dimension
A dimension whose length doesn't represent the true distance between the begin and end dimension points. Linear dimensions can be vertical, horizontal, or rotated. A vertical dimension's line represents the vertical distance between the begin and end dimension points. A horizontal linear dimension's line represents the horizontal distance between the begin and end dimension points. A rotated linear dimension is a dimension whose line is at some angle to the baseline and whose length represents the length of the dimension line itself, not the baseline.
linear feature
A geographic feature represented by a line or set of lines. A line connects two or more x,y coordinate pairs. Rivers, roads, and electric and telecommunication networks are all linear features.
linear units
The unit of measurement on a plane or a projected coordinate system, often meters or feet. Map projection parameters (such as the false easting and false northing) are defined in linear units.
line of sight
A graphic line between two points on a surface that shows whether or not the view along the line is obstructed.
local functions
This group of Spatial Analyst functions computes an output raster where the output value at each location is a function of the input value at the same location.
location query
Also called spatial query. Selection of features by their geometric relationship with other features. See also query.
logarithm functions
Functions within the Raster Calculator of Spatial Analyst. They perform exponential and logarithmic calculations on input grids and numbers.
There are six logarithmic functions: base e (Exp), base 10 (Exp10), and base 2 (Exp2) exponential capabilities, and natural (Log), base 10 (Log10), and base 2 (Log2) logarithmic capabilities.
logical network
An abstract representation of a network. A logical network consists of edge, junction, and turn elements and the connectivity between them. You can ask a logical network which elements are connected, but you cannot ask it for the geometry of these elements. A logical network does not contain any coordinate data, so you cannot ask it for the location of its elements. For this you need a geometric network. In a logical network, an edge element is connected to two junction elements (a from-junction and a to-junction), and a junction can have zero or more edges connected to it. A turn has a from-edge, a junction, and a to-edge. Each element can also have many weights associated with it. Weights are typically used to describe the cost to traverse an edge or turn or the cost to pass through a junction.
long transaction
An edit session on a feature dataset that may last from a few minutes to several months. Long transactions are managed by ArcSDE's versioning mechanism.
longitude
The angular distance (usually measured in degrees) east or west of a prime meridian.
longitude of center
The longitude value that defines the center (and sometimes origin) of a projection.
longitude of origin
The longitude value that defines the origin of the x-coordinate values for a projection.

M
macro
A sequence of commands that can be executed as one command. Macros can be written to perform frequently used or complex operations. In ArcCatalog and ArcMap, you use VBA to create macros.
major axis
The longer axis of an ellipse or spheroid.
make permanent
When using Spatial Analyst, this option creates a permanent raster from a temporary result from analysis.
map
A graphical representation of geographic information. It includes geographic data and other elements such as a title, North arrow, legend, and scale bar. You can interactively display and query the geographic data on a map and prepare a printable map by arranging the map elements around the data in a visually pleasing manner.
The document used in ArcMap to display and work with geographic data. A map contains one or more layers of geographic data and various supporting map elements such as a scale bar. Layers on a map are contained in data frames.
Map Algebra
The analysis language for the Spatial Analyst. It provides access to a wide range of additional functions not included in the user interface, and enables you to build more complex expressions and process them as a single command.
map display
A graphic representation of a map on the computer screen.
map document
In ArcMap, the disk-based representation of a map. Map documents can be printed or embedded in other documents. Map documents have an .mxd file extension.
map element
A graphic component, such as a scale bar, North arrow, title, or legend, that helps describe the geographic data on the map.
map feature
See feature.
Map LIBRARIAN
A set of software tools to manage and access large geographic datasets in a map library. Map LIBRARIAN commands create and define a map library, move data in and out of a library, query the data in a map library, and display the results of a query.
map projection
See projection.
map scale
See scale.
map surround
See map element.
map template
In ArcMap, a kind of map document that provides a quick way to create a new map. Templates can contain data, a custom interface, and a predefined layout that arranges map elements, such as North arrows, scale bars, and logos, on the virtual page. Map templates have an .mxt file extension.
map tips
Displays on-screen descriptions of map features when you pause the mouse pointer over the feature.
map units
The units—for example, feet, miles, meters, or kilometers—in which the coordinates of spatial data are stored.
mathematical functions
Functions within the Raster Calculator of Spatial Analyst. They apply a mathematical function to the values of a single input grid. There are four groups of mathematical functions available: logarithmic, arithmetic, trigonometric, and powers.
mathematical operators
Operators within the Raster Calculator of the Spatial Analyst. They apply a mathematical operation to the values in two or more input grids. There are three groups of mathematical operators available: Arithmetic, Boolean, and Relational.
Arithmetic: *, /, -, +
Boolean: And, Or, Xor, Not
Relational: ==, >, <, <>, .=, <=
menu
A command that arranges other commands into a list.
menu item
An item in a list of commands displayed from a menu.
merge policy
In geodatabases, all attribute domains have a merge policy associated with them. When two features are merged into a single feature in the Editor, the merge policies dictate what happens to the value of the attribute to which the domain is associated. Standard merge policies are default value, sum, and weighted average.
meridian
The reference line on the earth's surface formed by the intersection of the surface with a plane passing through both poles. This line is identified by its longitude. Meridians run north-south between the poles.
metadata
Information about GIS data describing a collection of data. Metadata for geographical data may include the source of the data, its creation date and format, its projection, scale, resolution, and accuracy, and its reliability with regard to some standard. ArcCatalog stores metadata in XML (extensible markup language), so the same metadata can be viewed in many different ways using different style sheets.
Metadata consists of properties and documentation. Properties are derived from the data source, while documentation is entered by a person. By default, ArcCatalog automatically creates and updates metadata, which is stored as well-formed XML data in a file alongside the data or within a geodatabase. Metadata for a folder can also consist of a well-formed HTML file describing its contents.
metadata element
One piece of data within a data source's metadata. In the XML file, each element has an opening and closing tag. Elements can appear many times in an XML file; these are called repeating elements. For example, in a shapefile's metadata, an "<attr>" element might represent one of its attributes. Therefore, the "<attr>" element will appear many times—once for each attribute.
metadata profile
An extension to the FGDC's Content Standard for Digital Geospatial Metadata. Additional elements defined by ESRI are recorded in the ESRI Metadata Profile.
method
An action that an object is capable of performing. Objects that belong to the same class all have the same methods. For example, all form objects can execute a method called "Show and Hide".
Microsoft Access
A commercial RDBMS used for the personal geodatabase.
Microsoft SQL Server
A commercial RDBMS that is supported with ArcSDE.
minimum bounding rectangle
A rectangle, oriented to the x- and y-axes, that bounds a geographic feature or a geographic dataset. It is specified by two coordinate pairs: xmin, ymin and xmax, ymax. For example, the extent defines a minimum bounding rectangle for a coverage.
minor axis
The shorter axis of an ellipse or spheroid.
model
An abstraction of reality used to represent objects, processes, or events.
A set of clearly defined analytical procedures used to derive new information.
A data representation of reality (for example, vector data model, TIN data model, raster data model).
mouse mode
Also known as relative mode, mouse mode is one of the ways in which a digitizing tablet operates. In mouse mode, the digitizer puck behaves just like a mouse; there is no correlation between the position of the screen pointer and the surface of the digitizing tablet, but you can choose interface elements with the pointer. See also digitizing mode.
MSDE
Microsoft Database Engine. A client/server data engine based on Microsoft SQL Server. Can be used with ArcSDE for SQL Server.
multipart feature
A feature that is composed of more than one physical part but only references one set of attributes in the database. For example, in a layer of states, the State of Hawaii could be considered a multipart feature. Although composed of many islands, it would be recorded in the database as one feature.
multipoint feature
A feature that consists of more than one point but only references one set of attributes in the database. For example, a system of oil wells might be considered a multipoint feature, as there is a single set of attributes for multiple well holes.
multiuser database
A geodatabase in an RDBMS served to client applications (for example, ArcMap) by ArcSDE. Multiuser geodatabases can be very large and support multiple concurrent editors. Supported on a variety of commercial RDBMS including Oracle, Microsoft SQL Server, IBM DB2, and Informix.

N
NAD 1927
North American Datum of 1927. A local datum and geographic coordinate system used in North America. Replaced by NAD 1983. Also known as NAD27.
NAD 1983
North American Datum of 1983. A geocentric datum and geographic coordinate system used in North America. Also known as NAD83.
natural neighbors
An interpolation method where cell values are estimated using weighted values of the input data points that are their natural neighbors, determined by creating a triangulation of the input points.
navigate
To interactively change the perspective view of a scene by moving the mouse.
nearest-neighbor resampling
Uses the value of the closest cell to assign a value to the output cell when resampling.
neatline
A border commonly drawn around geographic features, often to separate them from other map elements.
neighborhood statistics
A focal Spatial Analyst function that computes an output grid where the value at each location is a function of the input cells within a specified neighborhood of the location.
network
A set of edges and junctions that are topologically connected to each other. See also logical network.
network ancillary role
In a geometric network, junction features can act as sources or sinks for calculating flow direction. If a junction is a source or a sink, it is said to have an ancillary role in the network.
network feature
A feature that participates in a geometric network.
network trace
Navigates a network following connectivity defined by the geometric network. Specific kinds of network traces are:
Find connected
Find loops
Find common ancestors
Trace upstream
Trace downstream
See also geometric network.
nodata
Some rasters have empty cells within the area for which data was collected. For grids, these cells are nodata, while for other formats they are often assigned a special value, such as -9999. Rasters with some nodata cells are also created by some raster analysis tools, or Spatial Analyst's Reclassify function. You can control the display of nodata by setting the nodata color on the Symbology tab of the Layer Properties dialog box. See null value and background.
node
A location on a TIN surface at the intersection of two or more edges. Nodes on a TIN surface store elevation (z) values and may have tag values. Point features used to generate a TIN become nodes in the TIN. Additional nodes are added to the TIN at the intersection of edges.
normalize
Creating a ratio by dividing two data values. Normalizing data minimizes differences in values based on the size of areas or numbers of features in each area. For example, dividing a value by the area of a feature yields a value per unit area, or density.
North arrow
A map component that shows how a map is oriented.
NSDI
National Spatial Data Infrastructure. Coordinated by the FGDC. The NSDI encompasses policies, standards, and procedures for organizations to cooperatively produce and share geographic data. The NSDI is being developed in cooperation with organizations from state, local, and tribal governments; the academic community; and the private sector.
nugget
A parameter of a covariance or semivariogram model that represents independent error, measurement error, and/or microscale variation at spatial scales that are too fine to detect. The nugget effect is seen as a discontinuity at the origin of either the covariance or semivariogram model.
null value
The absence of a value. A geographic feature for which there is no associated attribute information.

O
object
In geodatabases, the representation of a real-world entity. An object has properties and behavior.
The interface by which an application program accesses an operating system and other services.
object class
While spatial objects (features) are stored in feature classes in a geodatabase, nonspatial objects are stored in object classes. A table is an object class if it has a column with the data type OID (Object Identifier), where each row in the table is an object. In a geodatabase, nonspatial objects can have custom behavior.
oblique aspect
A planar or cylindrical projection with its central point located at some point not on the equator or at the poles.
offset
To change the z-value for a surface or features in a scene by a constant amount or using an expression. Offsets may be applied to make features draw just above a surface.
OGC
OpenGIS Consortium. OpenGIS is defined as transparent access to heterogeneous geodata and geoprocessing resources in a networked environment. The goal is to provide a comprehensive suite of open interface specifications that enable developers to write interoperational components that provide these capabilities.
OLE DB provider
Object Linking and Embedding Database provider. Each provider communicates with and retrieves data from a different database, but you can work with data retrieved by any provider in the same way. Typically, they can only retrieve nonspatial data. However, if an OLE DB provider can retrieve geographic data in OpenGIS format, you can work with that data in ArcInfo.
operator
A mathematical symbol that performs an operation. Operators are provided in the Raster Calculator of Spatial Analyst to enable analysis to be performed within and between multiple rasters.
Oracle
A commercial RDBMS supported by ArcSDE.
origin
The primary object in a relationship. For example, a feature class containing points at which measurements are taken; the measurements are stored in the associated table. See also relationship and destination.
orthographic view
Allows you to view the data in a scene as a 2D plane seen from above. There is no perspective foreshortening in orthographic view, so scale is constant across the entire display.
Overlay wizard
An ArcToolbox wizard that uses overlay operations to create a new coverage by computing the geometric intersection of two coverages—an input coverage and an overlay coverage. See also identity, intersect, and union.
overshoot
That portion of an arc digitized past its intersection with another arc. See also dangling arc.

P
pan
To move the viewing window up, down, or sideways to display areas in a geographic dataset that, at the current viewing scale, lay outside the viewing window.
parallel
A reference line on the earth's surface that runs east–west around a sphere or spheroid and is parallel to the equator.
parametric curve
A curved segment that has only two vertices as endpoints, instead of being made of numerous vertices. When editing features in ArcMap, you can create a parametric curve using the Arc tool or the Tangent Curve command. Also known as a true curve.
password
The password used for authentication when you log in to an RDBMS.
path
The location of a file or directory on a disk. A path is always specific to the computer operating system.
path label
Describes the nature of the association between the objects in a relationship. The forward path label describes the relationship when navigating from the origin to the destination; for example, station points "have" measurements. The backward path label describes the same relationship navigating from the destination to the origin, which might be "are taken at" in this example; measurements "are taken at" stations.
PC ARC/INFO coverage
A coverage created with PC ARC/INFO.
percent slope
One way slope is measured. With this method, the rise is divided by the run.
permanent dataset
A raster dataset permanently stored on disk. All output raster results from Spatial Analyst are temporary, unless you specify a location on disk and a filename in a function dialog box, you make the temporary dataset permanent, or you save the map document. In these three cases, temporary results will become permanent datasets on disk. See make permanent.
personal geodatabase
A geodatabase, usually on the same network as the client application (for example, ArcMap), that supports one editor at a time. Personal geodatabases are managed in a Microsoft Jet Engine database.
perspective view
Allows you to view the data in a scene in 3D from a perspective that you can control by navigating the scene or from a specified position.
pixel
Picture element. A raster cell in images. See also raster cell.
planar coordinate system
A two-dimensional measurement system that locates features on a map based on their distance from an origin (0,0) along two axes, a horizontal x-axis representing east–west and a vertical y-axis representing north–south.
planar projection
A form of projection where the earth is projected onto a conceptual tangent or secant plane. Usually, a planar projection is the same as an azimuthal projection (Snyder and Voxland, 1989). See also tangent projection and secant projection.
planar topology
Represents collections of topological feature classes that share geometry among their boundaries. One or more line and polygon feature classes that share geometry participate in a common planar topology. Updating shared boundaries updates all features in the topology.
point
A single x,y coordinate pair that represents a single geographic feature such as a telephone pole.
point mode digitizing
One of two methods of digitizing features using the Sketch tool in ArcMap or from a paper map using a digitizer. With point mode digitizing, you can create or edit features by digitizing a series of precise points, or vertices. Point mode digitizing is effective when precise digitizing is required—for example, when digitizing a perfectly straight line. See also stream mode digitizing.
polar aspect
A planar projection with its central point located at either the North or South Pole.
polygon
A two-dimensional feature representing an area such as a state or county.
polygon–arc topology
A coverage polygon is made up of arcs that define the boundary and a label point that links the polygon feature to an attribute record in the coverage polygon attribute table (PAT). ArcInfo stores polygons topologically as a list of arcs and a label for each polygon.
polyline
A two-dimensional feature representing a line containing one or more line segments—that is, any line defined by three or more points. Line features such as boundaries, roads, streams, and streets are usually polylines.
port number
The TCP/IP port number on which an ArcSDE geodatabase instance is communicating.
post
During versioned geodatabase editing, posting is the process of applying the current edit session to the reconciled target version.
power functions
Functions within the Raster Calculator of Spatial Analyst. These functions apply a Power to the values in a single input raster. Three Power functions are available: Sqrt, Sqr, and Pow.
pre-7.0 coverage
Coverages created with a version of ArcInfo prior to version 7.0. Can't be accessed by ArcCatalog and ArcMap until after the ConvertWorkspace command has been used to modify the coverage workspace.
precision
Refers to the number of significant digits used to store coordinate values. Precision is important for accurate feature representation, analysis, and mapping. ArcInfo supports single and double precision.
preliminary topology
In coverages, refers to incomplete region topology. Region topology defines region-arc and region–polygon relationships. A topological region has both the region–arc relationship and the region–polygon relationship. A preliminary region has the region–arc relationship but not the region–polygon relationship. In other words, preliminary regions have no polygon topology. Coverages with preliminary topology have red in their icons in ArcCatalog.
preview
A live view of GIS data in ArcCatalog. You can pan and zoom the preview, query features, and create thumbnail images to store in metadata.
primary key
One or more attributes whose values uniquely identify a row in a database table.
Used to create a relationship class, the primary key resides in the origin object class. To join two object classes together, the primary key and foreign key must share the same values.
See also foreign key, relate, and relationship class.
prime meridian
A meridian of reference that defines the origin of the longitude values, 0° east or west.
profile graph
A graph of the height of a surface along a specified line.
projected coordinate system
A reference system used to measure horizontal and vertical distances on a planimetric map. A coordinate system is usually defined by a map projection, a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x- and y-directions to locate x,y positions of point, line, and area features.
In ArcInfo, a system with units and characteristics defined by a map projection. A common coordinate system is used to spatially register geographic data for a given area.
A reference system consisting of a set of points, lines, and/or surfaces, and set of rules used to define the positions of points in space either in two or three dimensions.
projected coordinates
A measurement of locations on the earth's surface expressed in a two-dimensional system that locates features based on their distance from an origin (0,0) along two axes, a horizontal x-axis representing east–west and a vertical y-axis representing north–south. A map projection transforms latitude and longitude to x,y coordinates in a projected coordinate system. See also geographic coordinates.
projection
A mathematical formula that transforms feature locations between the earth's curved surface and a map's flat surface. A projected coordinate system includes the information needed to transform locations expressed as latitude and longitude values to x,y coordinates. Projections cause distortions in one or more of these spatial properties: distance, area, shape, and direction.
property
An attribute of an object defining one of its characteristics or an aspect of its behavior. For example, the Visible property affects whether a control can be seen at run time. You can set a data source's properties using its Properties dialog box.
pyramids
In raster datasets, reduced resolution layers, or pyramids, record the original data in decreasing levels of resolution. The coarsest level of resolution is used to quickly draw the entire dataset. As you zoom in, layers with finer resolutions are drawn; performance is maintained because you're drawing successively smaller areas.

Q
query
A question or request used for selecting features. A query often appears in the form of a statement or logical expression. In ArcMap, a query contains a field, an operator, and a value.

R
radius
The distance from the center to the outer edge of a circle or circular curve.
range
A parameter of a variogram or semivariogram model that represents a distance beyond which there is little or no autocorrelation among variables.
range domain
A type of attribute domain. Specifies a valid range of values for a numeric attribute.
raster
Represents any data source that uses a grid structure to store geographic information. See grid and image.
raster band
A measure of some characteristic or quality of the features being observed in a raster. Some rasters have a single band; others have more than one. For example, satellite imagery commonly has multiple bands representing different wavelengths of energy from along the electromagnetic spectrum.
Raster Calculator
A Spatial Analyst function that provides a powerful tool for performing multiple tasks. You can perform mathematical calculations using operators and functions, set up selection queries, or type in Map Algebra syntax.
raster catalog
A collection of rasters defined in a table of any format, in which the records define the individual rasters that are included in the catalog. A raster catalog is used to display adjacent rasters without having to merge or mosaic them together into one large file.
raster cell
A discretely uniform unit (square or rectangle) that represents a portion of the earth such as a square meter or square mile. Each pixel has a value that corresponds to the feature or characteristic at that site such as a soil type, census tract, or vegetation class.
raster dataset
Contains raster data organized into bands. Each band consists of an array of cells with optional attributes for each cell (pixel).
raster model
A representation of the world as a surface divided into a regular grid of cells. Raster models are useful for storing data that varies continuously such as in an aerial photograph, a satellite image, a surface of chemical concentrations, or an elevation surface.
raster resolution
The size of the cells in a raster. Only features larger than or equal to the cell size can be discerned in a raster.
RDBMS
Relational database management system. A database management system with the ability to access data organized in tables that can be related to each other by a common field (column). An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage. ArcSDE supports several commercial RDBMS. See also database management system (DBMS).
reclassify
A Spatial Analyst function that takes input cell values and replaces them with new output cell values.
reconcile
In version management, reconciling is the process of merging all modified datasets, feature classes, and tables in the current edit session and a second target version. All features and rows that do not conflict are merged into the edit session, replacing the current features or rows. Features that are modified in more than one version are conflicts and require further resolution via the Conflict Resolution dialog box.
record
In an attribute table, a single "row" of thematic descriptors. In SQL terms, a record is analogous to a tuple.
A logical unit of data in a file. For example, there is one record in the ARC file for each arc in a coverage.
reference ellipsoid
See ellipsoid.
reference system
A method for identifying positions on the globe. This is often constructed with a grid that either refers to earth's latitude and longitude (graticule), or a planar equivalent that divides grid lines by a fixed length from a predefined point of origin.
referential integrity
A mechanism to ensure that data remains accurate and consistent as the database changes. When changes are made to a table related to another table by a common key, the changes are automatically reflected in both tables.
relate
An operation that establishes a temporary connection of records in two tables using an item common to both. See also relationship class and relational join.
relate manager
An ArcToolbox utility used to build, modify, save, and delete connections (relates) between tables. Saved connections can be reactivated in future ArcToolbox sessions.
relational database
A method of structuring data as collections of tables that are logically associated to each other by shared attributes. Any data element can be found in a relation by knowing the name of the table, the attribute (column) name, and the value of the primary key. See also RDBMS, relate, key attributes, and relational join.
relational database management system
See RDBMS.
relational join
The operation of relating and physically merging two attribute tables using their common item.
relational operators
Operators within the Raster Calculator of Spatial Analyst. These operators evaluate specific relational conditions. If a condition is TRUE, the output is assigned a value of 1. If the condition is FALSE, the output is assigned a value of 0.
Relational operators: ==, <, >, <>, >=, <=
relationship
An association or link between two objects in a database. Relationships can exist between spatial objects (features in feature classes), nonspatial objects (rows in a table), or between spatial and nonspatial objects.
relationship class
Objects in a real-world system often have particular associations with other objects in the database. These kinds of associations between objects in the geodatabase are called relationships. Relationships can exist between spatial objects (features in feature classes), between nonspatial objects (rows in a table), or between spatial and nonspatial objects. While spatial objects are stored in the geodatabase in feature classes, and nonspatial objects are stored in object classes, relationships are stored in relationship classes.
rematching
The process of regeocoding a subset of features in a geocoded feature class.
rendering
In 3D Analyst, the Rendering tab on the Layer Properties dialog box lets you control whether or not a layer is rendered during scene navigation, how it is shaded, and its drawing priority. It also lets you adjust how your computer's memory is allocated when rendering large images.
repository
A database that contains the schema information needed to create a geodatabase from a UML model created using a CASE tool.
resample
The process of extrapolating new cell values when transforming rasters to a new coordinate space or cell size. The three most common resampling techniques are nearest neighbor assignment, bilinear interpolation, and cubic convolution.
resolution
The accuracy at which a given map scale can depict the location and shape of geographic features. The larger the map scale, the higher the possible resolution. As the map scale decreases, resolution diminishes and feature boundaries must be smoothed, simplified, or not shown at all. For example, small areas may have to be represented as points.
The size of the smallest feature that can be represented in a surface.
The number of cells in the x- and y-directions in a raster.
rhumb line
A complex curve on the earth's surface that crosses every meridian at the same oblique angle; a straight line on the Mercator projection. Also called a loxodrome (Snyder and Voxland, 1989).
row
A record in an attribute table.
The horizontal dimension of a table composed of a set of columns containing one data item each.
A horizontal group of cells in a raster.

S
scale
The relationship between the dimensions of features on a map and the geographic objects they represent on the earth, commonly expressed as a fraction or a ratio. A map scale of 1/100,000 or 1:100,000 means that one unit of measure on the map equals 100,000 of the same unit on the earth.
scale bar
A map element that shows the map scale graphically.
scale factor
In a coordinate system, a value (usually less than one) that converts a tangent projection to a secant projection. Represented by "k0" or "k". If a projected coordinate system doesn't have a scale factor, the standard lines of the projection have a scale of 1.0. Other points on the map have scales greater or lesser than 1.0. If a projected coordinate system has a scale factor, the defining parameters no longer have a scale of 1.0.
scanning
The process of capturing data in raster format with a device called a scanner. Some scanners also use software to convert raster data to vector data.
scene
A document containing 3D data that can be viewed in perspective.
schema
The structure or design of a database or database object such as a table.
The definition of the database. The schema can either be modeled in UML using a CASE tool or defined directly within ArcCatalog using wizards.
SDE
See ArcSDE.
SDE 3 layer
A standalone feature class in a geodatabase built with SDE version 3. Can be served by an SDE 3 or ArcSDE 8 server.
secant projection
A form of map projection in which the conceptual surface of the projection (cone, cylinder, or plane) cuts through the earth's surface. See also tangent projection.
segment
A line that connects vertices. For example, in a sketch of a building, a segment would represent one wall.
select
To choose from a number or group of features or records; to create a separate set or subset.
Selectable layers list
A list available from the Selection menu in ArcMap that lets you choose which layers you want to select. For example, you might want to select a large number of buildings by drawing a box around them; but as you drew the selection box, you selected a parcel by mistake. To avoid this, you might uncheck the Parcels layer in the Selectable Layers list so that parcels cannot be selected.
selected values
A subset of the features in a layer or records in a table. ArcMap provides several ways to select features and records graphically or according to their attribute values.
selection anchor
When editing in ArcMap, a small "x" located in the center of selected features. The selection anchor is used when you move features using snapping. It is the point on the feature or group of features that will be snapped to the snapping location. This is also the point around which your selection will rotate when you use the Rotate tool and around which your feature will scale when you use the Scale tool in ArcMap.
semimajor axis
The equatorial radius of a spheroid. Often known as "a".
semiminor axis
The polar radius of a spheroid. Often known as "b".
semivariogram
The variogram divided by two.
server
A computer program that receives a request from a client, processes it to generate results, and returns the results to the client.
A computer on which a server process runs.
service
A computer program that receives and processes requests from clients.
shape
The characteristic appearance or visible form of a geographic object. Geographic objects can be represented on a map using one of three basic shapes: points, lines, or polygons.
shapefile
A vector data storage format for storing the location, shape, and attributes of geographic features. A shapefile is stored in a set of related files and contains one feature class.
shared boundary
A segment or boundary common to two features. For example, in a parcel database, adjacent parcels will share a boundary. Another example might be a parcel that shares a boundary on one side with a river. The segment of the river that coincides with the parcel boundary would share the same coordinates as the parcel boundary.
shared vertex
A vertex common to multiple features. For example, in a parcel database, adjacent parcels will share a vertex at the common corner.
shortcut key
A command's shortcut key executes the command directly without first having to open and navigate a menu. For example, Ctrl+C is a well-known shortcut for copying a file in Windows.
shortest path
A Spatial Analyst function that calculates the least-cost path from a destination point to the cheapest source, using the Cost Weighted Distance and Cost Weighted Direction datasets created via the Cost Weighted Distance function.
sill
A parameter of a variogram or semivariogram model that represents a value that the variogram tends to when distances become very large. At large distances, variables become uncorrelated, so the sill of the semivariogram is equal to the variance of the random variable.
simple edge feature
In geodatabases, a line feature that corresponds to a single network element in the logical network. See also complex edge feature.
simple feature
A feature that implements ESRI Simple Feature. A point, multipoint, line, polyline, or polygon.
simple junction feature
In a geodatabase, a junction feature that corresponds to a single network element in the logical network. See also complex junction feature.
simple relationship
Describes associations between data sources that exist independently of each other. A coverage and table are independent of each other if, when you delete the primary object, the related object continues to exist. For example, a table contains measurements taken at different stations. If you stop using a station and delete that point, you might keep the measurements for historical purposes.
single precision
Refers to a level of coordinate accuracy based on the number of significant digits that can be stored for each coordinate. Single precision numbers store up to seven significant digits for each coordinate, retaining a precision of ±5 meters in an extent of 1,000,000 meters. ArcInfo datasets can be stored as either single or double precision coordinates. See also double precision.
single-user geodatabase
A personal geodatabase. It can handle a single editor and multiple readers.
sink
In a network, a junction feature at which flow terminates. See also source.
sketch
When editing in ArcMap, a shape that represents a feature's geometry. Every existing feature on a map has this alternate form, a sketch. A sketch lets you see exactly how a feature is composed with all vertices and segments of the feature visible. To modify a feature, you must modify its sketch. To create a feature, you must first create a sketch. You can only create line and polygon sketches, as points have neither vertices nor segments.
Sketches help complete the current task. For example, the Create New Feature task uses a sketch you create to make a new feature. The Extend/Trim Feature task uses a sketch you create to determine where the selected feature will be extended or trimmed. The Cut Polygon Feature task uses a sketch you create to determine where the polygon will be cut into two features.
sketch constraints
In ArcMap editing, the angle or length limitations you can place on segments you're creating. These commands are available on the Sketch tool context menu. For example, you can set a length constraint that specifies that the length of the segment you're creating will be 50 map units. At whatever angle you create that segment, its length will be constrained to 50 map units. Angle constraints work in the same way. For example, you can set an angle constraint that specifies that the angle of the segment you're creating will be 45 degrees measured from another feature that already exists. At whatever length you create that segment, its angle will be constrained to 45 degrees.
sketch operations
In ArcMap, editing operations that are performed on an existing sketch. Examples are Insert Vertex, Delete Vertex, Flip, Trim, Delete Sketch, Finish Sketch, and Finish Part. All of these operations are available from the Sketch context menu, which is available when you right-click any part of a sketch using any editing tools.
slope
The incline, or steepness, of a surface. The slope of a TIN face is the steepest downhill slope of a plane defined by the face. The slope for a cell in a raster is the steepest downhill slope of a plane defined by the cell and its eight surrounding neighbors. Slope can be measured in degrees from horizontal (0-90) or percent slope, which is the rise divided by the run, times 100. A slope of 45 degrees equals 100 percent slope. As slope angle approaches vertical (90 degrees), the percent slope approaches infinity.
snap extent

A Spatial Analyst option. Setting the snap extent to a specific raster will snap all layers to the cell registration of the specified raster. All layers will share the lower-left corner and cell size of the specified raster. Use snap extent to resample layers to the same registration and cell size in order to perform analysis.
snapping
The process of moving a feature to coincide exactly with the coordinates of another feature within a specified snapping distance or tolerance.
snapping environment
Settings in ArcMap's Snapping Environment window and Editing Options dialog box that help you establish exact locations in relation to other features. You determine the snapping environment by setting the snapping tolerance, snapping properties, and snapping priority.
snapping priority
During ArcMap editing, the order in which snapping will occur by layer. You can set the snapping priority by dragging the layer names in the Snapping Environment window to new locations.
snapping properties
You can choose the part of a feature, vertex, edge, or endpoint to which you want a new feature to snap (precisely connect) by setting the layer snapping properties in ArcMap's editing environment. For example, you can set the snapping properties so that the endpoint of a new feature will snap to the vertex of an existing feature. When the pointer comes within the snapping tolerance of the vertex, the endpoint of the new feature snaps to the vertex of the existing feature.
snapping tolerance
During ArcMap editing, the distance within which the pointer or a feature will snap to another location. If the location being snapped to (vertex, boundary, midpoint, or connection) is within the distance you set, the pointer will automatically snap. For example, if you want to snap a power line to a utility pole and the snapping tolerance is set to 25 pixels, whenever the power line comes within a 25-pixel range of the pole it will automatically snap to it. Snapping tolerance can be measured using either map units or pixels.
source
In networks, a junction feature at which flow originates. See also sink.
A necessary input to the Cost Weighted Distance function of the Spatial Analyst. The source is the point or group of points that the Cost Weighted Distance function uses when calculating the accumulated cost of traveling through each cell to the nearest source.
spatial analysis
The study of the locations and shapes of geographic features and the relationships between them.
The process of modeling, examining, and interpreting model results. Spatial analysis is useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding. There are four traditional types of spatial analysis: topological overlay and contiguity analysis; surface analysis; linear analysis; and raster analysis.
spatial bookmark
In ArcMap, identifies a particular geographic location that you want to save and refer to later—for example, a study area.
spatial data
The locations and shapes of geographic features with descriptions of each feature.
spatial database
Any DBMS that contains spatial data.
spatial domain
Describes the range and precision of x,y coordinates, and z- and m-values that can be stored in a feature dataset or feature class in a geodatabase.
spatial function
An operation that performs spatial analysis. All spatial operations on Spatial Analyst user interface are classified spatial functions, for example, distance, slope, or density.
spatial join
A type of spatial analysis in which the attributes of features in two different layers are joined together based on the relative locations of the features.
spatial modeling
Analytical procedures applied with a GIS. Three categories of spatial modeling functions can be applied to geographic features within a GIS:
Geometric models (calculating the Euclidean distance between features, generating buffers, calculating areas and perimeters)
Coincidence models (topological overlay)
Adjacency models (pathfinding, redistricting, and allocation)
All three model categories support operations on spatial data, including points, lines, polygons, TINs, and grids. Functions are organized in a sequence of steps to derive the desired information for analysis. See also model and analysis.
spatial overlay
The process of superimposing layers of geographic data that occupy the same space in order to study the relationship between them.
spatial query
See location query.
spatial reference
Describes both the coordinate system and spatial domain extent for a feature dataset or feature class in a geodatabase.
sphere
A three-dimensional shape obtained by rotating a circle around an axis defined by its diameter.
spherical coordinate system
A reference system using positions of latitude and longitude to define the locations of points on the surface of a sphere or spheroid.
spheroid
When used to represent the earth, the three-dimensional shape obtained by rotating an ellipse about its minor axis. This is an oblate ellipsoid of revolution, also called an ellipsoid.
Spline
An interpolation method in which cell values are estimated using a mathematical function that minimizes overall surface curvature, resulting in a smooth surface that passes exactly through the input points.
split policy
In geodatabases, all attribute domains have a split policy associated with them. When a feature is split into two new features in ArcMap, the split policies dictate what happens to the value of the attribute with which the domain is associated. Standard split policies are duplicate, default value, and geometry ratio.
SQL
Structured Query Language. A syntax for defining and manipulating data from a relational database. Developed by IBM in the 1970s, it has become an industry standard for query languages in most relational database management systems.
standard line
A line on a sphere or spheroid that has no length compression or expansion after being projected. Commonly, a standard parallel or central meridian.
standard parallel
The line of latitude where the projection surface touches the surface. A tangent conic or cylindrical projection has one standard parallel, while a secant conic or cylindrical projection has two. A standard parallel has no distortion.
State Plane Coordinate System
A projected coordinate system used in the United States that divides each state into one or more zones to minimize distortion caused by the map projection. Also known as SPCS and SPC.
steepest path
A line that follows the steepest downhill direction on a surface. Paths terminate at the surface perimeter or in surface concavities or pits.
storage keywords
A set of parameters that specify how data and indexes are stored in an ArcSDE database. Keywords are stored in a table in the ArcSDE database.
straight line allocation
A Spatial Analyst function that identifies which cells belong to which source, based on closest proximity in a straight line.
straight line direction
A Spatial Analyst function that identifies the azimuth direction from each cell to the nearest source.
straight line distance
A Spatial Analyst function that calculates the distance in a straight line from every cell to the nearest source.
stream mode digitizing
One of two methods of digitizing features from a paper map. Also known as streaming, stream mode digitizing provides an easy way to capture features when you don't require high precision—for example, to digitize rivers, streams, and contour lines. Within stream mode, you create the first vertex of the feature and trace over the rest of the feature with the digitizer puck. You can also use digitize in stream mode when editing "freehand" by using the Sketch tool on the Editor toolbar. See also point mode digitizing.
stream tolerance
The interval at which vertices are added along the feature you're digitizing in stream mode. When streaming, vertices are automatically created at a defined interval as you move the mouse. For example, if the stream tolerance is set to 10 map units, you must move the pointer at least 10 map units before the next vertex will be created. If you move the pointer more than 10 map units, there may be more space between vertices, but there will always be a minimum interval of 10 map units. Stream tolerance is measured in map units. See also stream mode digitizing.
stretch
Applied to a raster to increase the visual contrast between its cells. It involves mapping original input values to a 0-255 scale.
suitability modeling
The process of creating a model to find optimum locations. A suitability model might identify suitable locations for a new facility or a road.
surface
A set of continuous data such as elevation or air temperature over an area, or the boundary between two distinct materials or processes.
style
An organized collection of elements that you use to make your maps or put on your maps. Styles include elements such as symbols, scale bars, North arrows, and colors. You might create different styles that contain the specific elements for the specific types of maps you make.
Style Manager
The tool that you use to create new styles and edit existing ones.
stylesheet
In metadata documents, an XSL stylesheet, which selects data from an XML file, applies functions and formatting to the data and then specifies how to present the data.
subtypes
In geodatabases, although all objects in a feature class or object class must have the same behavior and attributes, not all objects have to share the same default values and validation rules. You can group features and objects into subtypes. Subtypes differentiate objects based on their rules.
surface
A geographic phenomenon represented as a set of continuous data such as elevation or air temperature over an area. A clear or sharp break in values of the phenomenon (breaklines) indicates a significant change in the structure of the phenomenon, such as a cliff, not a change in geographic feature. Surfaces can be represented by models built from regularly or irregularly spaced sample points on the surface, or by contour lines, isolines, bathymetry, or the like.
Sybase
A commercial RDBMS.
symbol
A graphic pattern used to represent a feature. For example, line symbols represent arc features; marker symbols, points; shade symbols, polygons; and text symbols, annotation. Many characteristics define symbols including color, size, angle, and pattern.
symbology
The criteria used to determine symbols for the features in a layer. A characteristic of a feature may influence the size, color, and shape of the symbol used.