GIS Glossary/S

GIS Glossary

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S/A
The intentional degradation by the U.S. Department of Defense of the GPS signal for civilian receivers, which could cause errors in position of up to 100 meters. Selective availability (S/A) was removed from the civilian signal in May 2000. Since the lifting of S/A restrictions, position accuracy levels have improved to 20 meters or less.

satellite constellation
The arrangement of a set of satellites in space.

satellite imagery
Imagery acquired from satellites and aircraft, including panchromatic, radar, microwave, and multispectral satellite imagery.

saturation
The intensity or purity of a color; the perceived amount of white in a hue relative to its brightness, or how free it is of gray of the same value.

scalable
The ability to grow in size or complexity without showing negative effects.

scalable vector graphics
An XML-based graphics file format that describes two-dimensional vector images, including animation. SVG images scale to fit the display window without compromising quality.

scalar reference
In Survey Analyst, used to define measurement units based on a common standard.

scale
The ratio or relationship between a distance or area on a map and the corresponding distance or area on the ground, commonly expressed as a fraction or 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 used to graphically represent the scale of a map. A scale bar is typically a line marked like a ruler in units proportional to the map's scale.

scale factor
The reciprocal of the ratio used to specify scale on a map. For example, if the scale of a map is given as 1:50,000, the scale factor is 50,000.

Scale Palette
An ArcWeb Services tool that allows a user to view, add, delete, and modify scale ranges for feature classes.

scale range
The scales at which a layer is visible on a map. Scale ranges are commonly used to prevent detailed layers from displaying at small scales (zoomed out) and to prevent general layers from displaying at large scales (zoomed in).

scale viewer
A tool in the ArcWeb Services Web site that allows a user to see the current scale and move to different scale views.

scanner
A device that captures a print or hard-copy image, such as a text document or map, and records the information in digital format.

scanning
The process of capturing data from hard-copy maps or images in digital format using a device called a scanner.

scatter chart
A chart in which each data point is marked against perpendicular x- and y-axes. Scatter charts are frequently used in analysis to find data trends.

scene
In 3D Analyst, 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, view, index, stored procedure, or trigger. In a relational database, the schema defines the tables, the fields in each table, the relationships between fields and tables, and the grouping of objects within the database. Schemas are generally documented in a data dictionary. A database schema provides a logical classification of database objects.

schema synchronization
During geodatabase editing, the process of applying schema changes from a replica to the relative replica in a replica pair. Examples of schema changes include adding or dropping a field.

schema-only checkout
In ArcGIS 9.1 and previous versions, a type of checkout that creates the schema of the data being checked out in the checkout geodatabase but does not copy any data.

SCM
Acronym for Service Control Manager. An administrative tool that enables the creation and modification of system services. It effectively serves as the runtime environment for COM.

S-code
The standard PRN code used by most civilian GPS receivers.

scratch file
A file, created by either a software user or an operating system, that holds temporary data or results during an operation. When the operation is complete, the file is deleted.

scratch workspace
A path to a container for file-based geographic data that can be set in the Environment Settings dialog box or at the command line, into which all automatically generated outputs will be placed.

script
A set of computing instructions, usually stored in a file and interpreted at run time.

scrubbing
Checking the accuracy of data before it is converted into a different format.

SDC dataset
A collection of Smart Data Compression (SDC) feature classes sharing attribute information with different geometries. An SDC dataset is stored in a set of related files and contains multiple feature classes. SDC is the core data structure used in ArcGIS StreetMap, ArcIMS RouteServer, RouteMAP IMS, Business Analyst, and BusinessMAP.

SDC feature class
A highly compressed, read-only data structure that can store spatial geometry (points, lines, and polygons), and attribute data. The SDC structure supports geocoding, routing, and most spatial operations. SDC is the core data structure used in ArcGIS StreetMap, ArcIMS RouteServer, RouteMAP IMS, ArcGIS Business Analyst, and BusinessMAP.

SDE user
The account used to administer ArcSDE. The SDE user requires certain advanced database privileges to configure and manage ArcSDE geodatabases and ArcSDE services.

SDEHOME
A system environment variable that defines the location where ArcSDE software is installed.

sdesetup
A program run by a database administrator during ArcSDE installation or upgrade. The sdesetup program creates or upgrades the ArcSDE system tables. It is named differently for different databases; for example, the program used with Oracle 9i is called sdesetupora9i.

SDI
Acronym for spatial data infrastructure. A framework of technologies, policies, standards, and human resources necessary to acquire, process, store, distribute, and improve the use of geospatial data across multiple public and private organizations.

SDK
Acronym for software development kit. A set of code libraries and related tools used to develop platform-specific applications.

SDTS
Acronym for Spatial Data Transfer Standard. A data exchange format for transferring different databases between dissimilar computing systems, preserving meaning and minimizing the amount of external information needed to describe the data. All federal agencies are required to make their digital map data available in SDTS format upon request, and the standard is widely used in other sectors.

seamline
In ArcGIS Image Server, a polygon that defines the mosaic boundary of the raster dataset used in an image service. Overlapping raster datasets can be blended along the seamline by a specified width. Seamlines are created with the Seamline extension tools, and are stored as shapefiles within the image service definition.

search radius
The maximum distance in coverage units a feature can be from the current point for consideration as the closest feature. The default is the width or height of the near coverage BND (boundary) divided by 100, whichever is larger.

search tolerance
In network analysis, the threshold distance used to find the closest network element to a network location.

searching neighborhood
In spatial interpolation, a polygon that forms a subset of data around the prediction location. Only data within the searching neighborhood is used for interpolation.

seat
In software licensing, the number of simultaneous instances of software that can be used at one time. Most often, seats represent software users at individual computers. Seats may, however, also represent the simultaneous number of servers or connections in use.

SEC
The attribute table for the section feature class in a coverage, containing the route number and arc number to which the section belongs, the starting and ending positions expressed as percentages of the arc length, the starting and ending positions expressed as measures along the route, an internal sequence number, a section feature identifier, and user-defined attributes.

secant
A straight line that intersects a curve or surface at two or more points.

secant projection
A projection whose surface intersects the surface of a globe. A secant conic or cylindrical projection, for example, is recessed into a globe, intersecting it at two circles. At the lines of intersection, the projection is free from distortion.

second
An angle equal to one sixtieth of a minute of latitude or longitude.

second normal form
The second level of guidelines for designing table and data structures in a relational database. The second-normal-form guideline incorporates the guidelines of first normal form; in addition, it recommends removing data that applies to multiple rows in a table into its own table and using a foreign key to create a relationship to the original table. A database that follows these guidelines is said to be in second normal form.

secondary reference data
All material used as reference data in an address locator beyond the primary reference data. Secondary reference data can consist of an Alternate Name table or a Place-Name Alias table.

second-order stationarity
In geostatistics, the assumption that a set of data comes from a random process with a constant mean, and spatial covariance that depends only on the distance and direction separating any two locations.

section
The arcs or portions of arcs used to define a route.

section table
The attribute table for the section feature class in a coverage, containing the route number and arc number to which the section belongs, the starting and ending positions expressed as percentages of the arc length, the starting and ending positions expressed as measures along the route, an internal sequence number, a section feature identifier, and user-defined attributes.

Secure Sockets Layer
An encryption protocol for the secure transfer of private information over the Internet.

segment
In ArcGIS, a geometric element from which paths are constructed. A segment consists of a start point, an endpoint, and a function that describes a straight line or curve between these two points. Curves may be circular arcs, elliptical arcs, or Bézier curves.

select
To choose from a number or group of features or records; to create a separate set or subset.

selectable layers
Layers from which features can be selected in ArcMap with the interactive selection tools. Selectable layers can be chosen using the Set Selectable Layers command in the Selection menu, or on the optional Selection tab in the table of contents.

selected set
A subset of features in a layer, or records in a table, that is chosen by the software user.

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
In an ArcMap editing session, a small "x" located in the center of selected features. The selection anchor is used in the snapping environment, or when rotating, moving, and scaling features.

selection file
An ArcInfo Workstation file that stores the specifications of the selection criteria to be applied against specific coverages and INFO tables. It does not store the actual selected features or records, only the selection methods. Selection files are created with the WRITESELECT command in ArcPlot.

selective availability
The intentional degradation by the U.S. Department of Defense of the GPS signal for civilian receivers, which could cause errors in position of up to 100 meters. Selective availability (S/A) was removed from the civilian signal in May 2000. Since the lifting of S/A restrictions, position accuracy levels have improved to 20 meters or less.

self-organizing map
A map that uses a neural network algorithm to classify and illustrate associations in complex datasets, and reveal multidimensional patterns. A similar set of methods produces maps referred to as self-organizing maps (SOMs). Kohonen maps are named for the Finnish engineer Teuvo Kohonen.

semantics
The definition of the meaning of concepts within a data model by their relationships to other concepts.

semicross variogram
A function of the distance and direction separating two locations, used to quantify cross correlation. The cross variogram is defined as the variance of the difference between two variables of different types or attributes at two locations. The cross variogram generally increases with distance, and is described by nugget, sill, and range parameters.

semimajor axis
The equatorial radius of a spheroid, often referred to as "a."

semiminor axis
The polar radius of a spheroid, often referred to as "b."

semivariogram
The variogram divided by two.

sense of place
One's perception of the essential character of a place in which one resides or has resided, stemming from a personal response to the environment. Sense of place usually refers to perceptions of a neighborhood or city, but can also describe feelings about a larger region, state, or country.

sensitivity analysis
Analysis designed to test the robustness of model and analytical results to ensure that small changes in model parameters or data structure do not exhibit large changes in the results.

sensor
An electronic device for detecting energy, whether emitted or radiated, and converting it into a signal that can be recorded and displayed as numbers or as an image.

sequential analysis
Analysis based on a sample of an unfixed size in which testing continues only until a trend is observed with a predefined level of certainty.

serializable read
The isolation level in a database management system (DBMS) that offers the highest degree of isolation from concurrent transactions. All reads in the transaction only see data committed before the transaction began, and never see concurrent transaction changes committed during transaction execution.

serialization
A method of data conversion in which data is encoded as a sequence, stored in a file, memory buffer, or other medium, and transmitted across a network connection. Data is often serialized for transmission over phone lines or networks that require data to be sent one bit at a time.

serialization file
A file that stores serialized data.

server
A computer that manages shared resources, such as disks, printers, and databases, on a network.

server account
The operating system account that the server object manager service runs as. The server account is specified by the GIS server postinstallation utility.

server context
In ArcGIS, the environment on the GIS server within which a service or server object and its associated objects are running. A server context runs within a server container process. A developer gets a reference to a server object through the server object&#8217;s server context, and can create other objects within a server object's context.

server directory
A location on a file system used by a GIS server to retrieve map caches and write different types of output.

server object
In ArcGIS, an object that manages and serves a GIS resource, such as a map or a locator. A server object is a high-level object that simplifies the programming model for doing certain operations and hides the fine-grained ArcObjects that do the work. Server objects also have SOAP interfaces, which makes it possible to expose server objects as Web services that can be consumed by clients across the Internet. At ArcGIS 9.3, there are seven types of server objects: MapServer, GeocodeServer, GeodataServer, GeometryServer, GlobeServer, GPServer, and ImageServer.

server object isolation
In ArcGIS, a condition that describes whether multiple instances of a service can run within the same process. Services with high isolation run dedicated processes, whereas services with low isolation share processes with other services of the same type.

server product
Products that can be used on one enterprise server machine. Each server product requires a unique registration number used to generate the authorization file. The Software Authorization Wizard is then used to enter the authorization file and unlock the software for use.

server-side address locator
An address locator in which processing is done on one computer with the results accessible to other computers. Server-side address locators consist of services available over the Internet, via local area networks, or via an ArcSDE server.

service
A persistent software process that provides data or computing resources for client applications.

service area analysis
In ArcGIS Network Analyst, a type of network analysis for determining the region that encompasses all accessible streets (streets that lie within a specified impedance). For example, the 20-minute service area for a network location (such as a fire station) includes all the streets that can be reached within 20 minutes from that location.

service configuration file
In ArcIMS, the file that contains the core site information. ArcIMS configuration files contain all the basic information about the content to be delivered, such as location of the data and layer symbology. Typically, a configuration file contains data that defines map content and has a file extension of .axl, but it can also be used to deliver metadata or route data (as .axl files) and to serve maps created in ArcMap (.mxd or .pmf files). Regardless of their type, configuration files contain content that the service registers to the ArcIMS spatial server and Web server for processing.

service group
A bundle of data that covers a geographic area. Service groups are used for OpenLS and Mobile Toolkit requests.

service provider
A software program that receives service requests from clients, processes data, and serves it back to the client.

service table
In ArcGIS Image Server, a table defining links to multiple raster datasets and some service-specific attributes, including display range. A service table is stored as part of the footprint shapefile within an image service definition.

servlet
A Java platform technology for extending Web servers that provides a component-based, platform-independent method for building Web-based applications.

Servlet Connector
In ArcIMS, the default connector used to connect the ArcIMS Application Server to a Web server.

servlet engine
A Java platform technology that interfaces with a Web server and hosts servlets. Servlet engines provide a common application programming interface (API) that servlets use to build Web applications.

state
The process by which a Web application maintains information across a sequence of requests by the same client to the same Web application.

sextant
A handheld navigational instrument that measures, from its point of observation, the angle between a celestial body and the horizon or between two objects. The angle is measured on a graduated arc that covers one sixth of a circle (60 degrees).

SGML
Acronym for Standard Generalized Markup Language. A markup language with a predefined vocabulary and structure. SGML is used to structure information in a DTD, or Document Type Definition format, for exchanging information between different programs and machines. SGML uses a tag structure, and was standardized by ISO in 1986.

SHA1
Acronym for Secure Hash Algorithm v1. A Federal Information Processing Standards (FIPS) method for encoding sensitive information before sending the information over the Internet. The method jumbles data, such as passwords, so it is virtually impossible to recover the original information.

shade symbol
A color or pattern used to fill polygons on a map.

shaded relief image
A raster image that shows changes in elevation using light and shadows on terrain from a given angle and altitude of the sun.

shading
Graphic patterns such as cross hatching, lines, or color or grayscale tones that distinguish one area from another on a map.

shallowly stateful application
An application that uses the session state management capabilities of a Web server to maintain application state and makes stateless use of server objects. Shallowly stateful applications can use pooled server objects.

shape
The characteristic appearance or visible form of a geographic object as represented on a map. A GIS uses points, lines, and polygons to represent the shapes of geographic objects.

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 boundary common to two features. For example, in a parcel database, adjacent parcels share a boundary. Another example is a parcel that shares a boundary on one side with a river. The segment of the river that coincides with the parcel boundary shares the same coordinates as the parcel boundary.

shared content
In ArcWeb Services, data files, layers, and services that are available to more than one user.

shared vertex
A vertex common to multiple features. For example, in a parcel database, adjacent parcels share a vertex at the common corner.

sheet-fed scanner
A type of scanner that moves a document through a roller assembly over camera sensors that capture a digital image.

shield
A map symbol that serves as a route marker. Shields come in many varieties, but the most common shields in the United States are for interstate highways, U.S. routes, state routes, and county routes. A uniform standard exists for interstate highways, U.S. routes, and most county routes across the United States, while shields for state routes vary by state.

shift
Adding a constant value to a coordinate.

shortcut key
A keystroke combination that executes a command that might otherwise require the use of a mouse. For example, Ctrl+C is a well-known keyboard shortcut for copying a selection in Windows.

shortcut menu
A list menu that pops up when the right mouse button is clicked in Windows applications. Some keyboards also have an application key that opens shortcut menus.

shortest path
The best route or the route of least impedance between two or more points, taking into account connectivity and travel restrictions such as one-way streets and rush-hour traffic.

short-range variation
In a spatial model, fine-scale variation that is usually modeled as spatially-dependent random variation.

showcase application
A complete application that demonstrates a solution for a specific need. ArcWeb Services offers downloadable showcase applications, but they require some level of customization.

SIC codes
The federal U.S. standard for classifying establishments by their primary type of business activity. Standard Industrial Classification codes (SIC codes) are used as an identification system in business directories, publications, and statistical sources. The classification system was officially replaced by NAICS in 1997, but it is still used by some organizations outside the federal government.

side offset
An adjustable value that dictates how far away from either the left or right side of a line feature an address location should be placed. A side offset prevents a point feature from being placed directly over a line feature.

side-shot course
In Survey Analyst, used to compute a coordinate that is not a part of the main traverse course sequence.

signal
Information conveyed via an electric current or electromagnetic wave.

signal-to-noise ratio
The ratio of the information content of a signal to its noninformation content (noise).

signature
The pattern of electromagnetic radiation that identifies a chemical or compound. Materials can be distinguished from one another by examining which portions of the spectrum they reflect and absorb.

significance level
In statistical testing, the probability of an incorrect rejection of the null hypotheses.

sill
A parameter of a variogram or semivariogram model that represents a value that the variogram tends toward when distances become large. Under second-order stationarity, variables become uncorrelated at large distances, so the sill of the semivariogram is equal to the variance of the random variable.

simple edge feature
In a geodatabase, a line feature that corresponds to a single network element in the logical network.

simple feature
A point, line, or polygon that is not part of a geometric network and is not an annotation feature, dimension feature, or custom object.

simple junction feature
In a geodatabase, a junction feature that corresponds to a single network element in the logical network.

simple kriging
A kriging method in which the weights of the values do not sum to unity. Simple kriging uses the average of the entire dataset, which is less accurate than ordinary kriging but produces a smoother result.

simple market area
An area defined by a generalized boundary drawn around the most distant set of customer points (a convex hull) that total to some value. The calculation may be unweighted (in which case every point has the same value) or weighted by a value in the underlying database, such as sales.

simple measurement
The simplest form in which measurements from COGO sources or TPS (Total Positioning System) sources can be stored.

simple relationship
A link or association between data sources that exist independently of each other.

simple style
In ArcWeb Services, a single symbol used to display the features in a layer class at all scale ranges. Users can create simple styles.

simple temporal event
In ArcGIS Tracking Analyst, an event that contains all necessary information in one temporal data message (for real-time data) or record (for fixed-time data).

simplification
A type of cartographic generalization in which the important characteristics of features are determined and unwanted detail is eliminated to retain clarity on a map whose scale has been reduced.

simultaneous conveyance
A means of defining multiple units of land in a single survey document in such a way that all their boundaries have equal legal status. A common example of simultaneous conveyance is the modern subdivision.

single precision
A level of coordinate exactness 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 plus or minus 5 meters in an extent of 1,000,000 meters. Datasets can be stored in either single or double precision coordinates.

Single setup page
One of two types of setup pages in the Survey Analyst Survey Explorer. The single setup page is used for computations that process single instrument setups.

single threaded apartment
An apartment that has only a single thread. User interface code is usually placed in an STA.

single use
In software licensing, a software product that can be used on only one machine. AA

single-coordinate precision
A level of coordinate exactness 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 plus or minus 5 meters in an extent of 1,000,000 meters. Datasets can be stored in either single or double precision coordinates.

singleton
A class for which there can only be one instance in any process.

single-user geodatabase
A geodatabase that can handle a single editor and multiple readers.

sink
The location or group of locations used as the endpoint for distance analysis.

site prospecting
The process of evaluating demographic data surrounding potential locations for a business, based on a user-defined trade area or areas.

site starter
A downloadable ArcWeb Services application that users can customize and use on their site.

sketch
In ArcMap, a shape that represents a feature's geometry. Every existing feature on a map has this alternate form, a sketch, that allows visualization of that feature's composition, with all vertices and segments of the feature visible. When features are edited in ArcMap, the sketch is modified, not the original feature. A sketch must be created in order to create a feature. Only line and polygon sketches can be created, since points have neither vertices nor segments.

sketch constraint
In ArcMap editing, an angle or length limitation that can be placed on segments created using the Sketch tool.

sketch operation
In ArcMap, an editing operation that is 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 shortcut menu.

Sketch tool
In ArcMap, a tool that adds points, vertices, or segments to create an edit sketch. Sketch points can be defined by heads-up digitizing, snapping, or manually entering coordinates.

sliver polygon
A small, narrow, polygon feature that appears along the borders of polygons following the overlay of two or more geographic datasets. Sliver polygons may indicate topology problems with the source polygon features, or they may be a legitimate result of the overlay.

sliver removal
The act of deleting unwanted sliver polygons.

slope
The incline, or steepness, of a surface. Slope can be measured in degrees from horizontal (0&#8211;90), or percent slope (which is the rise divided by the run, multiplied by 100). A slope of 45 degrees equals 100 percent slope. As slope angle approaches vertical (90 degrees), the percent slope approaches infinity. 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 slope of a plane defined by the cell and its eight surrounding neighbors.

slope image
A raster image that shows changes in elevation using light and shadows on terrain from a given angle and altitude of the sun.

small circle
The circle made when a flat plane intersects a sphere anywhere but through its center. Parallels of latitude other than the equator are small circles.

small scale
Generally, a map scale that shows a relatively large area on the ground with a low level of detail.

smart pointer
A Visual C++ class implementation that encapsulates an interface pointer, providing operators and functions that can make working with the underlying type easier and less error prone.

smart style
In ArcWeb Services, a set of symbols used to display the features in a layer class at different scale ranges. Users can create smart styles.

smoothing
In image processing, reducing or removing small variations in an image to reveal the global pattern or trend, either through interpolation or by passing a filter over the image.

snap extent
An ArcGIS geoprocessing option that snaps, or aligns, all layers to the cell registration of a specified raster. All layers will share the lower left corner and cell size of the specified raster. Snap extent is used to resample layers to the same registration and cell size in order to perform analysis.

snap raster
An option in the Environment Setting dialog box that ensures the cell alignment of the extent will match accurately with an existing raster. This is done by snapping the lower left corner of the specified extent to the lower left corner of the nearest cell in the snap raster, and snapping the upper right corner of the specified extent to the upper right corner of the nearest cell in the snap raster.

snapping
An automatic editing operation in which points or features within a specified distance (tolerance) of other points or features are moved to match or coincide exactly with each others' coordinates.

snapping environment
Settings in the ArcMap Snapping Environment window and Editing Options dialog box that define the conditions in which snapping will occur. These settings include snapping tolerance, snapping properties, and snapping priority.

snapping priority
The order in which snapping will occur by layer during an ArcMap editing session, set from the Snapping Environment window.

snapping properties
In ArcMap editing, a combination of a shape to snap to and a method for determining what part of the shape will be snapped to. Snapping properties can be set to have a feature snap to a vertex, edge, or endpoint of features in a specific layer. For example, a layer snapping property might allow snapping to the vertices of buildings. A more generic, sketch-specific snapping property might allow snapping to the vertices of a sketch being created.

snapping tolerance
A specified distance within which points or features within are moved to match or coincide exactly with each others' coordinates.

SnapTip
In ArcMap, a user-assistance component that displays an on-screen description of the layer name or target being snapped to when the mouse pointer is paused over it. SnapTips only appear during an ArcMap edit session if they are enabled.

SNR
The ratio of the information content of a signal to its noninformation content (noise).

SOAP
An XML-based protocol developed by Microsoft, SAP, and IBM for exchanging information between peers in a decentralized, distributed environment. SOAP allows programs on different computers to communicate independently of an operating system or platform by using the World Wide Web's Hypertext Transfer Protocol (HTTP) and XML as the basis of information exchange. SOAP is used in Web services and is now a W3C specification. SOAP was originally an acronym for Simple Object Access Protocol</I>, but the acronym has fallen out of use.

SOC
Acronym for server object container</I>. A process in which one or more services is running, or the machine hosting this process. SOC processes are started and shut down by the SOM. The SOC processes run on the GIS server's container machines. Each container machine is capable of hosting multiple SOC processes.

software development kit
A set of code libraries and related tools used to develop platform-specific applications.

solution
A ready-to-use application geared toward a specific audience or industry. For example, ArcWeb Services solutions can be downloaded and used with little to no customization and accessed through a Web browser.

solver
A function that performs network analysis based on a set of network data.

SOM
Acronym for server object manager</I>. A Windows service that manages a set of server objects that are distributed across one or more server object container machines, or the machine on which this service is running. When an application makes a connection to an ArcGIS Server over a LAN, it is making a connection to the SOM.

sonar
Acronym for sound navigation and ranging</I>. A system or device that measures the time lapse between emitting a sound and receiving a returned echo to determine the location, depth and shape of objects under water. Certain types of sonar consist only of a listening device that picks up sound emitted by underwater objects, such as submarines.

soundex
A method of phonetic spelling used for searches and address matching. Soundex uses an algorithm to represent letters and numbers with similar phonetic equivalents to facilitate searching.

source
The location or group of locations used as the starting point for distance analysis.

source table
In ArcView 3.x, one of the two tables involved in a join operation. The source table must be the inactive table; its attributes are appended to the destination (active) table.

space coordinate system
A three-dimensional, rectangular, Cartesian coordinate system that has not been adjusted for the earth's curvature. In a space coordinate system, the x- and y-axes lie in a plane tangent to the earth's surface, and the z-axis points upward.

spaghetti data
Vector data composed of simple lines with no topology and usually no attributes. Spaghetti lines may cross, but no intersections are created at those crossings.

spaghetti digitizing
Digitizing that does not identify intersections as it records lines.

spatial
Related to or existing within space.

spatial adjustment
An ArcMap editing function that allows transformation, rubber sheeting, and edgematching of data, as well as attribute transfer.

spatial analysis
The process of examining the locations, attributes, and relationships of features in spatial data through overlay and other analytical techniques in order to address a question or gain useful knowledge. Spatial analysis extracts or creates new information from spatial data.

spatial autocorrelation
A measure of the degree to which a set of spatial features and their associated data values tend to be clustered together in space (positive spatial autocorrelation) or dispersed (negative spatial autocorrelation).

spatial bookmark
In ArcMap, a shortcut created by the user that identifies a particular geographic location to be saved for later reference.

spatial cognition
The mental processes involved in gaining and using knowledge and beliefs about spatial environments. Spatial cognition includes issues of perception, memory, language, learning, and problem solving, and is an object of study in humans, nonhuman animals, and machines.

spatial data
Information about the locations and shapes of geographic features and the relationships between them, usually stored as coordinates and topology.

spatial data infrastructure
A framework of technologies, policies, standards, and human resources necessary to acquire, process, store, distribute, and improve the use of geospatial data across multiple public and private organizations.

Spatial Data Transfer Standard
A data exchange format for transferring different databases between dissimilar computing systems, preserving meaning and minimizing the amount of external information needed to describe the data. All federal agencies are required to make their digital map data available in SDTS format upon request, and the standard is widely used in other sectors.

spatial database
A structured collection of spatial data and its related attribute data, organized for efficient storage and retrieval.

spatial dependence
A measure of the degree to which a set of spatial features and their associated data values tend to be clustered together in space (positive spatial autocorrelation) or dispersed (negative spatial autocorrelation).

spatial domain
For a spatial dataset in ArcGIS 9.1 and previous versions, the defined precision and allowable range for x- and y-coordinates and for m- and z-values, if present.

spatial function
In ArcGIS Spatial Analyst, an operation that performs spatial analysis. All Spatial Analyst tools in the Spatial Analyst toolbox, and operations on the ArcGIS Spatial Analyst toolbar, are classified as spatial functions. For example, distance, slope, and density are examples of spatial functions.

spatial grid
A two-dimensional grid system that spans a feature class. It is used to quickly locate features in a feature class that might match the criteria of a spatial search.

spatial index
In a geodatabase, a mechanism for optimizing access to data based on the spatial column of the business table. In most geodatabases, a system of grids is used for the spatial index. Exceptions to this are spatial indexes used in Oracle Spatial or Informix databases, which use R-tree indexes.

spatial join
A type of table join operation in which fields from one layer's attribute table are appended to another layer's attribute table based on the relative locations of the features in the two layers.

spatial modeling
A methodology or set of analytical procedures used to derive information about spatial relationships between geographic phenomena.

spatial overlay
The process of superimposing layers of geographic data that cover the same area to study the relationships between them.

spatial overlay analysis
A type of analysis in which data is extracted from one layer (such as block groups) to an overlay layer (such as a trade area).

spatial query
A statement or logical expression that selects geographic features based on location or spatial relationship. For example, a spatial query might find which points are contained within a polygon or set of polygons, find features within a specified distance of a feature, or find features that are adjacent to each other.

Spatial Query Web Service
A SOAP ArcWeb service that performs spatial queries and proximity searches.

spatial reference
In ArcGIS 9.2 or later, the coordinate system, tolerance, and resolution used to store a spatial dataset.

spatial reference system
A reference framework consisting of a set of points, lines, and/or surfaces, and a set of rules, used to define the positions of points in space in either two or three dimensions. The Cartesian coordinate system and the geographic coordinate system used on the earth's surface are common examples of coordinate systems.

spatial statistics
The field of study concerning statistical methods that use space and spatial relationships (such as distance, area, volume, length, height, orientation, centrality and/or other spatial characteristics of data) directly in their mathematical computations. Spatial statistics are used for a variety of different types of analyses, including pattern analysis, shape analysis, surface modeling and surface prediction, spatial regression, statistical comparisons of spatial datasets, statistical modeling and prediction of spatial interaction, and more. The many types of spatial statistics include descriptive, inferential, exploratory, geostatistical, and econometric statistics.

spatial weights matrix
A file that quantifies spatial relationships among a set of features. Typical examples of such relationships are inverse distance, contiguity, travel time, and fixed distance.

spatialization
The transformation of complex, multivariate, nonspatial data into a spatial representation located in an information space. The relative positioning of data elements within the spatial representation shows relationships between them. Spatialization is used to allow exploration of nonspatial data using spatial metaphors and spatial analysis.

specialty
In ArcGIS Network Analyst, an object used in vehicle routing problem (VRP) analysis. A specialty is used to represent a specific capability that may be required by certain orders and supported by certain routes. Orders requiring a given specialty may only be assigned to routes that also support that specialty. For example, an order may require an electrician, so it can only be serviced by a route that also supports the electrician specialty.

spectral resolution
The range of wavelengths that an imaging system can detect.

spectral signature
The pattern of electromagnetic radiation that identifies a chemical or compound. Materials can be distinguished from one another by examining which portions of the spectrum they reflect and absorb.

spectrometer
A photometer that measures the intensity of electromagnetic radiation as a function of its frequency. Spectrophotometers are usually used for measuring the visible portion of the spectrum.

spectrophotometer
A photometer that measures the intensity of electromagnetic radiation as a function of its frequency. Spectrophotometers are usually used for measuring the visible portion of the spectrum.

spectroscopy
The scientific study of how different chemicals and other substances absorb and reflect different parts of the electromagnetic spectrum.

spectrum
The entire range of wavelengths (frequencies) over which electromagnetic radiation extends.

spelling sensitivity
In geocoding, the degree to which the spelling variation of a street name is allowed during a search for likely match candidates. The lower the value, the more likely it is that additional candidates will be retrieved, and vice versa. This value is adjustable on the Address Locator Properties dialog box.

sphere
A three-dimensional shape whose center is equidistant from every point on its surface, made by revolving a circle around 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
A three-dimensional shape obtained by rotating an ellipse about its minor axis, resulting in an oblate spheroid, or about its major axis, resulting in a prolate spheroid.

spider diagram
A type of market analysis that draws lines from a set of geocoded points (usually customers) to a single, central point (usually a store). Desire lines can be weighted.

spike
An anomalous data point that protrudes above or below an interpolated surface.

spline
In mathematics, a piecewise polynomial function used to approximate a smooth curve in a line or surface.

spline interpolation
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 character
A user-designated character that divides long labels into two or more lines during the labeling process. There can be more than one split character.

split policy
All attribute domains in geodatabases 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.

SPOT
Acronym for Satellite Pour l&#8217;Observation de la Terre</I>. Earth observation satellites developed by Centre National d'Etudes Spatiales (CNES), the space agency of France. The SPOT satellites gather high-resolution imagery used in natural resource management, climatology, oceanography, environmental monitoring, and the monitoring of human activities.

spot elevation
An elevation measurement taken at a single location.

spot height
An elevation measurement taken at a single location.

spurious polygon
A small, narrow, polygon feature that appears along the borders of polygons following the overlay of two or more geographic datasets. Sliver polygons may indicate topology problems with the source polygon features, or they may be a legitimate result of the overlay.

SQL
Acronym for Structured Query Language</I>. A syntax for retrieving and manipulating data from a relational database. SQL has become an industry standard query language in most relational database management systems.

SSL
Acronym for Secure Sockets Layer</I>. An encryption protocol for the secure transfer of private information over the Internet.

STA
Acronym for single threaded apartment</I>. An apartment that has only a single thread. User interface code is usually placed in an STA.

stable base
In cartography, any material such as a Mylar sheet or film that is more durable than paper and less likely to shrink or stretch.

stack
In computing, a data storage structure that operates on last in, first out (LIFO) protocol. As with a stack of dishes, the item placed on top of the stack last must be removed before the others may be manipulated.

staging geodatabase
A normalized, fixed set of feature classes and data tables of a predefined schema from a collection of input CAD drawings.

stand-alone application
An application that runs by itself, not within an ArcGIS application.

standard annotation
Annotation that is stored in the geodatabase, consisting of geographically placed text strings that are not associated with features in the geodatabase.

standard deviation
A statistical measure of the spread of values from their mean, calculated as the square root of the sum of the squared deviations from the mean value, divided by the number of elements minus one. The standard deviation for a distribution is the square root of the variance.

standard deviation classification
A data classification method that finds the mean value, then places class breaks above and below the mean at intervals of either .25, .5, or 1 standard deviation until all the data values are contained within the classes. Values that are beyond three standard deviations from the mean are aggregated into two classes, greater than three standard deviations above the mean and less than three standard deviations below the mean.

standard distance
A measure of the compactness of a spatial distribution of features around its mean center. Standard distance (or standard distance deviation) is usually represented as a circle where the radius of the circle is the standard distance.

Standard Generalized Markup Language
A markup language with a predefined vocabulary and structure. SGML is used to structure information in a DTD, or Document Type Definition format, for exchanging information between different programs and machines. SGML uses a tag structure, and was standardized by ISO in 1986.

Standard Industrial Classification codes
The federal U.S. standard for classifying establishments by their primary type of business activity. Standard Industrial Classification codes (SIC codes) are used as an identification system in business directories, publications, and statistical sources. The classification system was officially replaced by NAICS in 1997, but it is still used by some organizations outside the federal government.

standard line
A line on a sphere or spheroid that has no length compression or expansion after being projected; usually a standard parallel or central meridian.

standard parallel
The line of latitude in a conic or cylindrical projection in normal aspect where the projection surface touches the globe. A tangent conic or cylindrical projection has one standard parallel, while a secant conic or cylindrical projection has two. At the standard parallel, the projection shows no distortion.

star diagram
A type of diagram that consists essentially of a central point from which lines radiate outward. The central point usually represents a geographic location while the length of each line represents an attribute value or ratio. The direction of the line may represent a compass direction, a period of time, or some other attribute classification. A wind rose is a common example of a star diagram.

starter application
A ready-to-use Web application that is designed for a specific purpose, such as a store locator or a map viewer. Starter applications do not require customization before use.

state
In programming, the current data contained by an object.

state plane coordinate system
A group of planar coordinate systems based on the division of the United States into more than 130 zones to minimize distortion caused by map projections. Each zone has its own map projection and parameters and uses either the NAD27 or NAD83 horizontal datum. The Lambert conformal conic projection is used for states that extend mostly east&#8211;west, while transverse Mercator is used for those that extend mostly north&#8211;south. The oblique Mercator projection is used for the panhandle of Alaska.

state tree
A logical organization of all the states in the geodatabase. A state tree illustrates and maintains the logical relationship between states of a versioned geodatabase.

stateful operation
In programming, an operation that makes changes to an object or one of its associated objects, such as removing a layer from a map.

stateless
In programming, not retaining changes between calls. A stateless object or application does not store parameters or values from the last time it was called, so it is always in its original state.

stateless operation
An operation that does not make changes to an object, such as drawing a map.

static binding
A COM technique an application uses to access an object. In early binding, an object's properties and methods are discovered from an interface at compile time, instead of being checked at run time as in late binding. This difference often gives early binding performance benefits over late binding. There are two types of early binding: DispID binding and vTable binding.

static positioning
Determining a position on the earth by averaging the readings taken by a stationary antenna over a period of time.

stationarity
In geostatistics, a property of a spatial process in which all statistical properties of an attribute depend only on the relative locations of attribute values.

stationing
In the pipeline industry, another name for linear referencing. Stationing allows any point along a line feature representing a pipeline to be uniquely identified by its relative position along the line feature.

statistic F
A ratio of variances, calculated from a sample of data and used to provide information about a whole dataset. For example, statistic F may be used to provide estimates of variance, or differences, in a population, based on observations from two or more random samples.

statistical surface
Ordinal, interval, or ratio data represented as a surface in which the height of each area is proportional to a numerical value.

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.

steradian
The solid (conical) angle subtended at the center of a sphere of radius r</I> by a bounded region on the surface of the sphere having an area r</I> squared. There are 4&#960; steradians in a sphere.

stereocompilation
A map produced with a stereoscopic plotter using aerial photographs and geodetic control data.

stereogrammatic organization
The presentation of features on a map in a way that implies relative importance, usually achieved with visual contrast.

stereographic projection
A tangent planar projection that views the earth's surface from a point on the globe opposite the tangent point.

stereometer
A stereoscope containing a micrometer for measuring the effects of parallax in a stereoscopic image.

stereomodel
The three-dimensional image formed where rays from points in the images of a stereoscopic pair intersect.

stereopair
Two aerial photographs of the same area taken from slightly different angles that when viewed together through a stereoscope produce a three-dimensional image.

stereoplotter
An instrument that projects a stereoscopic image from aerial photographs, converts the locations of objects and landforms on the image to x-, y-, and z-coordinates, and plots these coordinates as a drawing or map.

stereoscope
A binocular device that produces the impression of a three-dimensional image from two overlapping images of the same area.

stereoscopic pair
Two aerial photographs of the same area taken from slightly different angles that when viewed together through a stereoscope produce a three-dimensional image.

sticky move tolerance
When editing in ArcMap, a setting that defines the minimum number of pixels the pointer must move on the screen before a selected feature is moved.

stochastic model
A model that includes a random component. The random component can be a model variable, or it can be added to existing input data or model parameters.

stop
In ArcGIS Network Analyst, a network location used to determine a route in route analysis. Users can specify multiple stops, of which two must be used to represent an origin and a destination. Stops in between (known as intermediary stops) are visited en route from the first to the last stop.

stop impedance
In network analysis, the time it takes for a stop to occur, used to compute the impedance of a path or tour. For example, when a school bus drops children off or picks them up at their homes, the stop impedance might be 2 minutes at each stop.

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.

store market analysis
A type of business analysis that uses mostly data about a store or stores, rather than about customers. Examples include ring studies and analyses of equal competition areas and drive-time areas.

store prospecting
A type of business analysis that assesses the potential of a site by performing simple ring or drive-time analysis.

straight-line allocation
An ArcGIS Spatial Analyst function that identifies which cells belong to which source, based on closest proximity in a straight line.

straight-line direction
An ArcGIS Spatial Analyst function that identifies the azimuth direction from each cell to the nearest source.

straight-line distance
An ArcGIS Spatial Analyst function that calculates the distance in a straight line from every cell to the nearest source.

stream
A mode of data delivery in which objects provide data storage. Stream objects can contain any type of data in any internal structure.

stream digitizing
A method of digitizing in which, as the cursor is moved, points are recorded automatically at preset intervals of either distance or time.

stream mode digitizing
A method of digitizing in which, as the cursor is moved, points are recorded automatically at preset intervals of either distance or time.

stream tolerance
During stream mode digitizing, the minimum interval between vertices. Stream tolerance is measured in map units.

streaming
A technique for transferring data, usually over the Internet, in a real-time flow as opposed to storing it in a local file first. Streaming allows large multimedia files to be viewed before the entire file has been downloaded to a client's computer. When received by the client (local computer) the data is uncompressed and displayed using software designed to interpret and display the data rapidly.

street network
A system of interconnecting lines and points that represent a system of roads for a given area. A street network provides the foundation for network analysis; for example, finding the best route or creating service areas.

street-based mapping
A form of digital mapping that links information to geographic locations and displays address locations as point features on a map.

stretch
A display technique applied to the histogram of raster datasets, most often used to increase the visual contrast between cells.

string
A set of coordinates that defines a group of linked line segments.

structure
The general pattern of z-values throughout a kriging model. The drift, or structure, forms the model's basic shape.

structure line
A line feature enforced in a TIN. There are two types of structure lines: hard and soft. Hard structure lines, also known as breaklines, represent interruptions in the slope of the surface. Soft structure lines are used to add information about the surface without implying a change in the surface behavior across the line.

Structured Query Language
A syntax for retrieving and manipulating data from a relational database. SQL has become an industry standard query language in most relational database management systems.

study area
The geographic area treated in an analysis.

style
An organized collection of predefined colors, symbols, properties of symbols, and map elements. Styles promote standardization and consistency in mapping products.

Style Manager
The tool used to create new styles and edit existing ones. The Style Manager displays the contents of all the styles that are currently referenced by the map. It also contains personal and additional styles that may be used in ArcMap.

style sheet
A file or form that provides style and layout information, such as margins, fonts, and alignment, for tagged content within an XML or HTML document. Style sheets are frequently used to simplify XML and HTML document design, since one style sheet may be applied to several documents. Transformational style sheets may also contain code to transform the structure of an XML document and write its content into another document.

subfield
In ArcGIS, a subset of all the fields associated with a layer or data.

sublayer
One of several layers that are part of a group layer in a map document.

subsumption
Within a geometric network, the replacement of an orphan junction by a non-orphan junction from a user-defined feature class. The original junction is deleted from the network, and the non-orphan junction assumes the connectivity of the subsumed orphan junction.

subtractive primary colors
In printing, the three primary colors&#8212;cyan, magenta, and yellow&#8212;that when used as filters for white light remove blue, green, and red light, respectively.

subtype
In geodatabases, a subset of features in a feature class or objects in a table that share the same attributes. For example, the streets in a streets feature class could be categorized into three subtypes: local streets, collector streets, and arterial streets. Creating subtypes can be more efficient than creating many feature classes or tables in a geodatabase. For example, a geodatabase with a dozen feature classes that have subtypes will perform better than a geodatabase with a hundred feature classes. Subtypes also make editing data faster and more accurate because default attribute values and domains can be set up. For example, a local street subtype could be created and defined so that whenever this type of street is added to the feature class, its speed limit attribute is automatically set to 35 miles per hour.

suitability model
A model that weights locations relative to each other based on given criteria. Suitability models might aid in finding a favorable location for a new facility, road, or habitat for a species of bird.

supplemental contour
A contour line placed between regularly spaced contours, used when the terrain change is not large enough to be depicted with consistent contour intervals.

surface
A geographic phenomenon represented as a set of continuous data (such as elevation, geological boundaries, or air pollution); a spatial distribution which associates a single value with each position in a plane, usually associated with continuous attributes.

surface fitting
Generating a statistical surface that approximates the values of a set of known x,y,z points.

surface mode
A navigation mode in ArcGlobe in which the camera target is always on the globe surface.

surface model
A representation of a geographic feature or phenomenon that can be measured continuously across some part of the earth's surface (for example, elevation). A surface model is an approximation of a surface, generalized from sample data. Surface models are stored and displayed as rasters, TINs, or terrains.

surface smoothness
Perpendicular or normal to the slope of the surface in 3D Analyst. As changes in slope are approached across the surface, the degree of smoothness is defined by how gradual or abrupt the normals to that surface change. A smooth surface has gradual changes in the normals to the surface; a planar surface has abrupt changes.

surround element
In digital cartography, a distinctly identifiable graphic or object in the map or page layout. For example, a map element can be a title, scale bar, legend, or other map-surround element. The map area itself can be considered a map element; or an object within the map can be referred to as a map element, such as a roads layer or a school symbol.

survey class
In Survey Analyst for field measurements, a collection of survey objects of a particular type. A survey dataset contains a set of survey classes for each of the different types of measurements and computations. There is also a survey class for coordinates and a survey class for survey points.

survey data converters
In Survey Analyst for field measurements, importers that interpret operation codes and feature codes when a data collector file is imported. Users choose the converter that matches the data collector file format.

survey dataset
In Survey Analyst for field measurements, a dataset that stores survey objects.

Survey Explorer
In Survey Analyst for field measurements, the main interface for working with stored survey information. Data may be explored and edited directly in the Survey Explorer. Users can add lists of coordinates, measurements, and computations to the Survey Explorer so they can view and analyze numerical values of measurements and coordinates created in their survey dataset.

survey layers
In Survey Analyst for field measurements, layers that are created whenever survey datasets or survey projects are added to the map. Survey layers appear in the table of contents of a map document and comprise a set of sublayers for survey points and measurements.

survey marker
An object, such as a metal disk, permanently mounted in the landscape to denote a survey station.

survey monument
An object, such as a metal disk, permanently mounted in the landscape to denote a survey station.

survey network
In Survey Analyst for field measurements, a sequence of computation dependencies&#8212;the output points of some computations are used as the input for one or more others.

survey objects
In Survey Analyst for field measurements, a collective term referring to measurements, computations, survey points, and coordinates in the survey dataset.

survey points
In Survey Analyst for field measurements, named locations that are observed through various surveys. Survey points can be observed multiple times and by many surveys over time. They represent multiple coordinates, but each identifies discrete physical locations on the earth's surface.

survey project
In Survey Analyst for field measurements, a subset of the survey dataset that represents a unit of work. A survey project is used as a logical structure that owns and manages a group of measurements, points, coordinates, and computations that function and belong together.

survey station
A location on the earth that has been accurately determined by geodetic survey.

survey-aware feature classes
In Survey Analyst for field measurements, the feature classes in the geodatabase that contain survey-aware features.

survey-aware features
In Survey Analyst for field measurements, features that are associated with survey data.

surveying
Measuring physical or geometric characteristics of the earth. Surveys are often classified by the type of data studied or by the instruments or methods used. Examples include geodetic, geologic, topographic, hydrographic, land, geophysical, soil, mine, and engineering surveys.

SVG
Acronym for scalable vector graphics</I>. An XML-based graphics file format that describes two-dimensional vector images, including animation. SVG images scale to fit the display window without compromising quality.

SWF
A vector-based Flash file format that supports text, audio, video, and end-user interaction. SWF files are often used to publish animations on the Web.

SXD
Scene document. A document saved by ArcScene that has an .sxd extension.

Sybase
A commercial RDBMS.

symbol
A graphic used to represent a geographic feature or class of features. Symbols can look like what they represent (trees, railroads, houses), or they can be abstract shapes (points, lines, polygons) or characters. Symbols are usually explained in a map legend.

Symbol ID code
A 15-character identifier that provides the information necessary to display or transmit a tactical symbol between MIL-STD-2525B compliant systems.

symbol level drawing
In ArcGIS, a setting that determines the drawing order of features based on their symbol. When symbols have more than one layer, symbol level drawing can be used to specify the order in which each layer of the symbol is drawn.

symbol library
A collection of symbols.

symbol modifier field
In MOLE, a defined area in which optional text or graphics may be entered to provide additional information about a force element or tactical graphic.

symbolization
The process of devising a set of marks of appropriate size, color, shape, and pattern, and assigning them to map features to convey their characteristics at a given map scale.

symbology
The set of conventions, rules, or encoding systems that define how geographic features are represented with symbols on a map. A characteristic of a map feature may influence the size, color, and shape of the symbol used.

synchronization
In geodatabase editing, the process of applying changes made from a replica to the relative replica in a replica pair.

synchronization version
In geodatabase editing, the geodatabase version that receives changes during synchronization. The synchronization version is always a child of the replica version. With one-way and two-way replication, the synchronization version is automatically reconciled and posted with the replica version. If there are conflicts between the synchronization version and the replica version, the conflicts must be resolved before more data changes can be sent.

synchronous
Occurring together, or at the same time.

syntax
The structural rules for using statements in a command or programming language.

system tool
In ArcGIS, a geoprocessing tool. System tools are stored in system toolsets and can be copied to custom toolsets and/or toolboxes.

system toolbox
In ArcGIS, a default geoprocessing toolbox that is installed with ArcGIS. System toolboxes contain system tools, organized into toolsets for ease of access.

system toolset
In ArcGIS, a subset of a geoprocessing toolbox that holds system tools.

systematic error
In Survey Analyst, one type of measurement error. Systematic error follows a mathematical or physical law, and it can be corrected to comply with a known standard.