GIS Glossary/P

GIS Glossary

0-9 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

packet
In Survey Analyst - Cadastral Editor, an XML stream or file containing the portion of the cadastral fabric that has been extracted by a cadastral fabric job for editing.

page unit
The unit of measure, usually millimeters or inches, used to arrange map elements on a page for printing, as opposed to the coordinate system on the ground that the map represents.

pan
To shift a map image relative to the display window without changing the viewing scale.

pan sharpening
Sharpening a low-resolution multiband image by merging it with a high-resolution panchromatic image.

panchromatic
Sensitive to light of all wavelengths in the visible spectrum.

panchromatic image
A single band image generally displayed as shades of gray.

panchromatic sharpening
Sharpening a low-resolution multiband image by merging it with a high-resolution panchromatic image.

paneled map
A map spliced together from smaller maps of neighboring areas.

parallax
The apparent shift in an object's position when it is viewed from two different angles.

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

parallel
An imaginary east&#8211;west line encircling the earth, parallel to the equator and connecting all points of equal latitude. Also, the representation of this line on a globe or map.

parallel processing
In computer data communications, a method of storing or sending data side by side, in groups of bits. Parallel data transmission is most often used for printer ports.

parameter
One of the variables that define a specific instance of a map projection or a coordinate system. Parameters differ for each projection and can include central meridian, standard parallel, scale factor, or latitude of origin.

parametric curve
A curve that is defined mathematically rather than by a series of connected vertices. A parametric curve has only two vertices, one at each end.

parcel
A piece or unit of land, defined by a series of measured straight or curved lines that connect to form a polygon.

parcel construction
In Survey Analyst - Cadastral Editor, a set of dimensions entered to create a set construction line work.

parcel group
In Survey Analyst - Cadastral Editor, a set of parcels that exist as a group instead of individually in a cadastral fabric job.

parcel PIN
Acronym for parcel identification number. In Survey Analyst - Cadastral Editor, a unique identifier for a parcel. The format of an identifier is defined by the government's organization, and may contain numerical values, alpha characters, or both.

parcel type
A classification for parcels, used to provide additional information about them and how they must be treated for least squares adjustment. Standard parcels, blocks, and easements are all examples of parcel types.

parent replica
In geodatabase editing, data in a source geodatabase that is replicated.

parity
The even or odd property of an integer. In address matching, parity is used to locate a geocoded address on the correct side of the street (such as odd numbers on the left-hand side, even numbers on the right).

parse
In computing, to divide a sequence of letters and numbers into parts, especially to test their agreement with a set of syntax rules.

partial address support
The ability to return a list of geocoding candidates based on incomplete address information. For example, if a city name but no country is entered in a partial address support search, the result list contains cities whose names match the name entered.

partial cache
In ArcGlobe, an on-demand cache that contains levels of detail for areas that have been visited, or a pre-processed cache that has a specified, incomplete, level of detail range for the entire layer.

partial sill
A parameter of a covariance or semivariogram model that represents the variance of a spatially autocorrelated process without any nugget effect. In the semivariogram model, the partial sill is the difference between the nugget and the sill.

passive remote sensing
A remote-sensing system, such as an aerial photography imaging system, that only detects energy naturally reflected or emitted by an object.

passive sensors
Imaging sensors that can only receive radiation, not transmit it.

password
A string of characters that a user must enter to access a computer, program, database, or Web site. Passwords are a means of protecting and restricting access to information contained on networks, systems, or files.

patch
A single triangular face inside a multipatch geometry. In most cases, many patches (faces) are used together to create a complex 3D model. Examples include geometric shapes, such as spheres, cubes, and tubes; geographic features, such as buildings, cars, and light poles; and other boundary representations, such as isosurfaces, used to represent geologic structures or environmental plumes. Patches in a multipatch geometry may or may not include an image (texture) displayed on them.

path
The connecting lines, arcs, or edges that join an origin to a destination.

path distance analysis
In ArcGIS Spatial Analyst, a description of each cell's least accumulative cost relationship to a source or a set of sources, accounting for surface distance, horizontal cost factors and vertical cost factors.

path label
A label that 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.

pathfinding
The process of calculating the optimal path between an origin and a destination point or points in a network.

pattern recognition
In image processing, the computer-based identification, analysis, and classification of objects, features, or other meaningful regularities within an image.

P-code
The PRN code used by United States and allied military GPS receivers.

PDF
Acronym for Portable Document Format. A proprietary file format from Adobe that creates lightweight text-based, formatted files for distribution to a variety of operating systems.

PDOP
Acronym for dilution of precision. An indicator of satellite geometry for a constellation of satellites used to determine a position. Positions with a lower DOP value generally constitute better measurement results than those with higher DOP. Factors determining the total GDOP (geometric DOP) for a set of satellites include PDOP (positional DOP), HDOP (horizontal DOP), VDOP (vertical DOP), and TDOP (time DOP).

peak
The highest point of a mountain or hill.

percent slope
A measurement of the rate of change of elevation over a given horizontal distance, in which the rise is divided by the run and then multiplied by one hundred. A 45-degree slope and a 100-percent slope are the same.

performance
A measure of the speed at which a computer system works. Factors affecting performance include availability, throughput, and response time.

perigee
In an orbit path, the point at which the object in orbit is closest to the center of the body being orbited.

permanent dataset
A dataset permanently stored on disk.

permanent license
A license that has a time-out date listed as permanent, indicating that the license for a particular product does not expire.

persistence
In computing, the process of saving or storing data; retaining the current state of an object in a memory storage medium such as a database or file on disk.

personal geodatabase
A geodatabase that stores data in Microsoft Access. A personal geodatabase can be read simultaneously by several users, but only one user at a time can edit the same data.

perspective view
A projection mode in 3D applications that allows viewing from a perspective that can be controlled by navigating the scene or globe from a specified location.

photogeology
The science of interpreting and mapping geologic features from aerial photographs or remote-sensing data.

photogrammetry
The science of making reliable measurements of physical objects and the environment by measuring and plotting electromagnetic radiation data from aerial photographs and remote-sensing systems against land features identified in ground control surveys, generally in order to produce planimetric, topographic, and contour maps.

photomap
An aerial photograph or photographs, referenced to a ground control system and overprinted with map symbology.

photometer
An instrument that records the intensity of light by converting incident radiation into an electrical signal and then measuring it.

physical geography
The field of geography concerning the natural features of the earth's surface.

physical network
One of the two parts of a network system; the actual feature classes that participate in a network system.

picture fill
A type of fill pattern created by continuous tiling of either a .bmp (raster image) or a .emf (vector graphic) file.

pie chart
A chart shaped like a circle cut into wedges from a center point, that represents percentage values as proportionally sized "slices." Pie charts are used to represent the relationship between parts and the whole.

pinch-roller
A printing device that draws an image onto large-size paper or transparencies. Although pen and electrostatic plotters have largely been replaced by large-format inkjet printers, the term plotter is still frequently used to refer to all large print devices.

pinning
In ArcGlobe, anchoring a vector graphic element to the underlying globe surface so that it remains fixed.

pit
A depression in the earth's surface.

pixel
The smallest unit of information in an image or raster map, usually square or rectangular. Pixel is often used synonymously with cell.

pixel size
The dimensions on the ground of a single pixel in a raster, measured in map units. Pixel size is often used synonymously with cell size.

pixel space
The x,y coordinate space defined by the number of pixels in a computer's display area, with a pixel being a single unit of color on the screen. Most computer displays support several pixel configurations (800 x 600, 1024 x 768, 1600 x 1200, and so on). The more pixels there are, the smaller each pixel is for a given display size. Since a pixel is a piece of information, a configuration with more pixels can fit more information into a given display area.

pixel type
The attribute of a variable, field, or column in a table that determines the kind of data it can store. Common data types include character, integer, decimal, single, double, and string.

place
In census geography, any incorporated or unincorporated city, town, or community.

Place Finder Sample Web Service
A free sample of the Place Finder Web Service. This sample demonstrates the "find a place" functionality available in the Place Finder Web Service and is provided only to sample ArcWeb Services.

Place Finder Web Service
A SOAP ArcWeb service that offers "find a place" functionality for Internet applications. Users can use the Place Finder Web Service to input a place-name and receive a ranked candidate list of place-names and associated coordinates. The Place Finder Web Service recognizes more than three million place-names, including geographic regions (such as continents, states, cities), bodies of water, and major points of interest.

place-name alias
The formal or common name of a location, such as the name of a school, hospital, or other landmark. For example, "Memorial Hospital" is the place name for the address "893 Memorial Drive." In geocoding, the address locator can be set to accommodate the use of place-name aliases in place of their addresses for matching.

plan
In surveying, a high-level organization of parcels; a survey document containing data from a recorded subdivision survey plan, or from a legal description. Often, many parcels are defined in one plan. In the Survey Analyst - Cadastral Editor cadastral fabric, plans hold such information about the subdivision plan record as the date, surveyor, entry units, scale factor, and so on. Each parcel contains a reference to a plan.

planar coordinate system
A two-dimensional measurement system that locates features on a plane based on their distance from an origin (0,0) along two perpendicular axes.

planar enforcement
A set of rules used to define a consistent method of building point, line and polygon features from spaghetti-digitized data. For example, planar enforcement includes rules that polygons of differing soil types cannot overlap, and that lines must be split at intersections.

planar projection
A projection that transforms points from a spheroid or sphere onto a tangent or secant plane. Because its directions are often true, the planar projection is also known as an azimuthal or zenithal projection.

planarize
The process of creating multiple line features by splitting longer features at the places where they intersect other line features. This process is often applied to nontopological line work that has been spaghetti digitized or imported from a CAD drawing.

plane survey
A survey of a small area that does not take the curvature of the earth's surface into account.

planimetric
Two-dimensional; showing no relief.

planimetric base
A two-dimensional map that serves as a guide for contour mapping, usually prepared from aerial photographs.

planimetric map
A map that displays only the x,y locations of features and represents only horizontal distances.

planimetric shift
Deviations in the horizontal positions of features in an aerial photograph caused by differences in elevation. Planimetric shift causes changes in scale throughout a photograph.

plat
A survey diagram, drawn to scale, of the legal boundaries and divisions of a tract of land.

platform
In computing, the operating system of a machine, such as the UNIX, Linux, or Windows operating systems. Platform may also refer to a programming language or development environment, such as COM, Java, or ArcGIS 9.

playback mode
The time mode in which data is displayed using the ArcGIS Tracking Analyst Playback Manager, replaying either real-time or fixed-time data.

Playback window
The span of time defined by the Start and End text boxes in the ArcGIS Tracking Analyst Playback Manager. This window can be set to include the temporal extent of one or more layers.

plotter
A printing device that draws an image onto large-size paper or transparencies. Although pen and electrostatic plotters have largely been replaced by large-format inkjet printers, the term plotter is still frequently used to refer to all large print devices.

PLSS
Acronym for Public Land Survey System. The description of the location of land in the United States using a survey system established by the federal government in 1785. The system is based on the concept of a township, a square parcel of land measuring 6 miles on each side. The township's position is described as a number of 6-mile units east or west of a north&#8211;south line (called the meridian) and north or south of an east&#8211;west line (called the baseline). Each township is divided into 36 sections, each of which is 1 square mile. A section is divided into quarters equal to 160 acres. The quarter section may be further divided into four 40-acre parcels. The PLSS is also called the rectangular survey.

PLTS
Acronym for Production Line Tool Set. A software package that allows users to prepare and maintain data for maps, perform quality assurance/quality control tasks, and create map sheets. Its base product, PLTS Foundation, is composed of three parts: Foundation Tools, GIS Data ReViewer, and Map Production System and MPS-Atlas. The tools can be used with different product specifications, and are available as solutions that have been created for nautical, defense, aeronautical, and mapping agencies.

PLTS data loader
A tool used to batch load a personal or enterprise geodatabase from a variety of sources (coverages, shapefiles, or geodatabases). The PLTS data loader uses a cross-reference database to map the input schema to the output schema.

PLTS Map Gallery
In PLTS, a tool for managing layer representation, such as symbology and label expressions.

plug-in
A small software application that extends the functionality of a Web browser.

plug-in data source
An additional read-only data source provided by either ESRI or a third-party developer. It may be a data source forming part of the core ArcObjects or an extension.

plumb line
A line that corresponds to the direction of gravity at a point on the earth's surface; the line along which an object will fall when dropped.

PMC
A geodatabase designed to manage database and map production for the Production Line Tool Set (PLTS). The PMC stores metadata and geometries of projects, products and source material.

PMF
Acronym for Published Map File. A file exported by the Publisher extension that can be read by ArcReader. Publisher Map Files end with a .pmf extension.

PNG
Acronym for Portable Network Graphics. A bitmapped graphics format similar to GIF.

POI Manager Web Service
A SOAP ArcWeb service for uploading a custom set of points. POI Manager is available as a Web interface and a SOAP interface.

point
A geometric element defined by a pair of x,y coordinates.

point and coordinate analysis
In Survey Analyst, part of the validation of survey data. This type of analysis is used to authenticate the relationships between survey points, coordinates, and the physical locations they represent.

point digitizing
A method of digitizing in which the digitizer selects particular points, or vertices, to encode.

point event
In linear referencing, a feature that occurs at a precise point location along a route and uses a single measure value. Examples include accident locations along highways, signals along rail lines, bus stops along bus routes, and pumping stations along pipelines.

point feature
A map feature that has neither length nor area at a given scale, such as a city on a world map or a building on a city map.

point identifier field
A field in the Survey Analyst Survey Explorer dialog box that allows a user to specify the name of a particular survey point.

point mode digitizing
A method of digitizing in which the digitizer selects particular points, or vertices, to encode.

point name flag
In Survey Analyst, a visual indicator, after each keystroke, of whether or not a point with the typed name already exists in the survey dataset.

point name prefix
In Survey Analyst, a unique part of every survey project. Points have a common name space across all projects of a survey dataset. However, different points in different projects can have the same name. When making use of these points, users can use the prefix of the survey project before the point's name to uniquely identify it. This ensures that the correct point is used.

point size
A unit of measure for fonts, nearly equal to 1/72 of an inch.

point thinning
Act of reducing point data in a dataset. Point thinning reduces the number of point measurements needed to represent a surface for a given area.

point-in-polygon overlay
A spatial operation in which points from one feature dataset are overlaid on the polygons of another to determine which points are contained within the polygons.

point-on-line overlay
In linear referencing, the overlay of a line event table and a point event table to produce a single point event table. The new event table can be the logical intersection or union of the input tables.

polar aspect
A planar projection with its central point located at either the north or south pole.

polar flattening
A measure of how much an oblate spheroid differs from a sphere. The flattening equals the ratio of the semimajor axis minus the semiminor axis to the semimajor axis.

polar orbit
A satellite orbit with an inclination near 90 degrees that passes over each polar region.

polar radius
The distance from the earth's geometric center to either pole.

polygon
On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

polygon feature
A map feature that bounds an area at a given scale, such as a country on a world map or a district on a city map.

polygon overlay
The process of superimposing two or more geographic polygon layers and their attributes to produce a new polygon layer.

polygon-arc topology
In a polygon coverage, the list of topologically connected arcs that define the boundary of a polygon feature and the label point that links it to an attribute record in the coverage point attribute table.

polyhedron
A three-dimensional object or volume defined by a number of plane faces or polygons.

polyline
In ArcGIS software, a shape defined by one or more paths, in which a path is a series of connected segments. If a polyline has more than one path (a multipart polyline), the paths may either branch or be discontinuous.

polyline feature
In ArcGIS software, a digital map feature that represents a place or thing that has length but not area at a given scale. A polyline feature may have one or more parts. For example, a stream is typically a polyline feature with one part. If the stream goes underground and later reemerges, it might be represented as a multipart polyline feature with discontinuous parts. If the stream diverges around an island and then rejoins itself, it might be represented as a multipart polyline feature with branching parts. A multipart polyline feature is associated with a single record in an attribute table.

port number
A number that is used to specify direct communication over a network to an Internet application.

portal
A Web resource that provides access to a broad array of related resources and services.

portlet
A Web component that processes requests and generates dynamic content. Portlets are used in portals as pluggable user interfaces to add specialized content, such as weather information, news, or maps, to Web pages. Users can customize the content, appearance, and position of a portlet.

position
The latitude, longitude, and altitude (x,y,z coordinates) of a point, often accompanied by an estimate of error. Position may refer to an object's orientation (facing east, for example) without referring to its location.

postal code
A series of letters or numbers, or both, in a specific format, used by the postal service of a country to divide geographic areas into zones in order to simplify delivery of mail.

posting
During versioned geodatabase editing, the process of applying the current edit session to the reconciled target version.

power
The number of times a value is to be multiplied by itself, indicated by an exponent. For example, 2 3=2*2*2.

precise code
The PRN code used by United States and allied military GPS receivers.

precision
The closeness of a repeated set of observations of the same quantity to one another. Precision is a measure of the control over random error. For example, assessment of the quality of a surveyor's work is based in part on the precision of their measured values.

precision code
The PRN code used by United States and allied military GPS receivers.

prediction
In spatial modeling, the process of forming a statistic from observed data to assign values to random variables at locations where data has not been collected.

prediction standard error
A value quantifying the uncertainty of a prediction; mathematically, the square-root of the prediction variance. (The prediction variance is the variation associated with the difference between the true and predicted value.) As a rule, 95 percent of the time the true value will lie within the predicted value plus or minus two times the prediction standard error if data is normally distributed.

preferences
User-specified settings that determine how an application will act or appear when it is used.

prefix pin
Used within the Survey Analyst Survey Explorer's Point Identifier field to separate the prefix and point name strings.

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.

preprocessed cache
In ArcGlobe, a cache that is built prior to viewing, using an independent process accessed from the shortcut menu of a layer.

Presentation Service
An OpenLS ArcWeb service used for generating map images.

preview
A live view of GIS data in ArcCatalog. Users can pan and zoom the preview, query features, and create thumbnail images to store in metadata.

primary colors
Colors from which all other colors are derived in a particular color system. On a display monitor, these colors are red, green, and blue. In printing, they are cyan, magenta, and yellow. In traditional pigments, they are red, blue, and yellow.

primary key
An attribute or set of attributes in a database that uniquely identifies each record. A primary key allows no duplicate values and cannot be null.

primary reference data
In geocoding, the most basic reference material used in an address locator, usually consisting of the geometry of features in a region and an associated address attribute table.

primary table
In geocoding, the attribute table associated with the primary reference data. Based on the address locator style selected, certain address elements must be present in the primary table.

prime meridian
In a coordinate system, any line of longitude designated as 0 degrees east and west, to which all other meridians are referenced. The Greenwich meridian is internationally recognized as the prime meridian for most official purposes, such as civil timekeeping.

prime vertical
In astronomy and geodesy, the vertical circle that passes through an observer's zenith and through the east and west points of the horizon.

primitive
In MOLE, the most elementary part of a graphic. Icon, frame, and fill are examples of components that make up MOLE graphics.

private virtual server
An ArcIMS virtual server that offers functionality not directly accessible when creating a Web site. The functionality associated with each of the three private ArcIMS virtual servers (geocode server, query server, and extract server) is called from within a service created using a public virtual server. For example, if you incorporate an image service with a geocodable street network into a Web site with the Geocode tool, a client can access the geocode server's functionality. The geocode virtual server works with the image virtual server to perform address matching and other geocoding functions.

PRJ
Usually a text file named prj.adf that is associated with a coverage, GRID, or TIN. The PRJ file contains the coordinate system information for the data. In a more general sense, PRJ can refer to the coordinate system of data even if the information is not stored in a prj.adf file. For example, "The PRJ of the shapefile is WGS 1984 UTM zone 15 north."

PRN
Acronym for pseudo-random noise</I>. A signal carrying a code that can be reproduced exactly, but appears to be randomly distributed like noise. Each NAVSTAR satellite has a unique PRN code.

PRN code
Acronym for pseudo-random noise code</I>. A repeating radio signal broadcast by each GPS satellite and generated by each GPS receiver. In a given cycle, the satellite and the receiver start generating their codes at the same moment, and the receiver measures how much later the satellite's broadcast reaches it. By multiplying that time by the speed of radio waves, the receiver can compute the distance between the satellite's antenna and its own.

probability
A measure of the likelihood that a particular outcome, such as a spatial pattern or event, will occur given a set of possible outcomes. Probability values range from 0 for impossible outcomes to 1 for completely certain outcomes. The probability that a tossed coin will land heads-up, for example, is 0.5, since landing heads-up is one of two possible outcomes.

probability map
A surface that gives the probability that the variable of interest is above or below a specified threshold value.

procedure
In software, a block of code that performs some task. Procedures are commonly used to organize code into reusable units. In object-oriented programming, a procedure that is specific to an object or class is called a method.

process
In geoprocessing in ArcGIS, a tool and its parameter values. One process, or multiple processes connected together, creates a model.

process chain
In ArcGIS Image Server, a list of raster processes that are performed on the fly by the server on raster data. The full process chain contains the raster dataset process applied to the raster data before mosaicking, and the service process applied after mosaicking.

Production Line Tool Set
A software package that allows users to prepare and maintain data for maps, perform quality assurance/quality control tasks, and create map sheets. Its base product, PLTS Foundation, is composed of three parts: Foundation Tools, GIS Data ReViewer, and Map Production System and MPS-Atlas. The tools can be used with different product specifications, and are available as solutions that have been created for nautical, defense, aeronautical, and mapping agencies.

profile graph
A graph of the elevation of a surface along a specified line.

ProgID
A string value, stored in the system registry, identifying a class by library and class name, for example esriCarto.FeatureLayer. The ProgID registry key also contains the human-readable name of a class, the current version number of the class, and a unique class identifier. ProgIDs are used in VB object instantiation.

project
In Survey Analyst, a specific task for capturing survey data. This can include anything from a field control survey to data entry from a subdivision plan.

Project and Map Sheet Catalog
A geodatabase designed to manage database and map production for the Production Line Tool Set (PLTS). The PMC stores metadata and geometries of projects, products and source material.

project data
Any data in a process that existed before the process existed.

project file
In ArcView 3, a file for creating and storing documents for GIS work. All activity in ArcView 3 takes place within project files, which use five types of documents to organize information: views, tables, charts, layouts, and Avenue scripts. A project file organizes its documents and stores their unique settings in an ASCII format file with the extension .apr.

project repair
In an ArcView 3.x project, the process of updating document paths when referenced document data is moved from one disk location to another. Project repair can be avoided if a system variable is entered as part of the document path and set within the necessary system file(s).

projected coordinate system
A reference system used to locate x, y, and z positions of point, line, and area features in two or three dimensions. A projected coordinate system is defined by a geographic coordinate system, a map projection, any parameters needed by the map projection, and a linear unit of measure.

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&#8211;west and a vertical y-axis representing north&#8211;south. Projected coordinates are transformed from latitude and longitude to x,y coordinates using a map projection.

projection
A method by which the curved surface of the earth is portrayed on a flat surface. This generally requires a systematic mathematical transformation of the earth's graticule of lines of longitude and latitude onto a plane. Some projections can be visualized as a transparent globe with a light bulb at its center (though not all projections emanate from the globe's center) casting lines of latitude and longitude onto a sheet of paper. Generally, the paper is either flat and placed tangent to the globe (a planar or azimuthal projection) or formed into a cone or cylinder and placed over the globe (cylindrical and conical projections). Every map projection distorts distance, area, shape, direction, or some combination thereof.

projection transformation
The mathematical conversion of a map from one projected coordinate system to another, generally used to integrate maps from two or more projected coordinate systems into a GIS.

projective transformation
A transformation used only to transform coordinates digitized directly from high-altitude aerial photographs of relatively flat terrain, assuming there is no systematic distortion in the photographs.

prolate ellipsoid
An ellipsoid created by rotating an ellipse around its major axis.

property
An attribute of an object defining one of its characteristics or an aspect of its behavior.

property file
A file that stores attributes for a particular ArcIMS item or function. Property files have a .properties file extension.

property page
A user interface component that provides access to change the properties of an object or objects.

proportional symbol
A symbol whose size differs in relation to the phenomenon being mapped.

protected code
The PRN code used by United States and allied military GPS receivers.

proximity analysis
A type of analysis in which geographic features (points, lines, polygons, or raster cells) are selected based on their distance from other features or cells.

proximity query
A form of spatial query in which geographic features within a specified distance of a particular feature are selected.

Proximity Web Service
A SOAP ArcWeb service for finding all point-of-interest (POI) locations within a distance of a specified point or line (for example, find all POIs within five miles of x,y) or for determining the nearest specified number of POI locations to a specified point or line (such as find nearest three POIs to x,y).

proxy object
A local representation of a remote object, supporting the same interfaces as the remote object. All interaction with the remote object from the local process is mediated via the proxy object. A local object makes calls on the members of a proxy object as if it were working directly with the remote object.

pseudo node
In a geodatabase topology, a temporary feature marking the location where an edge has been split during an edit session. This type of pseudo node becomes a vertex when the edit is saved.

pseudo-random noise
A signal carrying a code that can be reproduced exactly, but appears to be randomly distributed like noise. Each NAVSTAR satellite has a unique PRN code.

pseudo-random noise code
A repeating radio signal broadcast by each GPS satellite and generated by each GPS receiver. In a given cycle, the satellite and the receiver start generating their codes at the same moment, and the receiver measures how much later the satellite's broadcast reaches it. By multiplying that time by the speed of radio waves, the receiver can compute the distance between the satellite's antenna and its own.

Public Land Survey System
The description of the location of land in the United States using a survey system established by the federal government in 1785. The system is based on the concept of a township, a square parcel of land measuring 6 miles on each side. The township's position is described as a number of 6-mile units east of a north&#8211;south line (called the meridian) and north or south of an east&#8211;west line (called the baseline). Each township is divided into 36 sections, each of which is 1 square mile. A section is divided into quarters equal to 160 acres. The quarter section may be further divided into four 40-acre parcels. The PLSS is also called the rectangular survey.

public participation
The active involvement of stakeholders outside an organization in the decision-making or planning processes of that organization. Public participation in GIS processes may include making GIS tools and data accessible, at an appropriate technical level, to stakeholders, or it may result in knowledge gained from stakeholders being incorporated into GIS analyses.

public virtual server
An ArcIMS virtual server that must be specified when creating a new service. Three public virtual servers install with ArcIMS: image server, feature server, and metadata server. Two additional public virtual servers, ArcMap server and route server, are optional extensions to ArcIMS.

publish
To produce data and information in a distributable format, such as digital, Internet, or print media.

Published Map File
A file exported by the Publisher extension that can be read by ArcReader. Publisher Map Files end with a .pmf extension.

publisher
Software that converts raw information into a more usable format.

puck
The handheld device used with a digitizer to record positions from the tablet surface.

pull check-in
In ArcGIS 9.1 and previous versions, a check-in operation initiated from a master geodatabase.

push broom scanner
A remote-sensing tool with a line of many fixed sensors that record reflected radiation from the terrain along a satellite's direction of movement, creating scan-line strips that are contiguous or that overlap slightly, thereby producing an image.

push check-in
In ArcGIS 9.1 and previous versions, a check-in operation initiated from a checkout geodatabase.

p-value
A probability resulting from a statistical test of the coefficient associated with each independent variable in a regression model. The null hypothesis for this statistical test states that the coefficient is not significantly different from zero. Small p-values reflect small probabilities. They suggest that the coefficient is significantly different from zero, and consequently, that the associated explanatory variable is helping to model or predict the dependent variable. Variables with coefficients near zero do not help predict or model the dependent variable; they are almost always removed from the regression equation (unless there are strong theoretical reasons to keep them).

pyramid
In raster datasets, a reduced resolution layer that copies the original data in decreasing levels of resolution to enhance performance. The coarsest level of resolution is used to quickly draw the entire dataset. As the display zooms in, layers with finer resolutions are drawn; drawing speed is maintained because fewer pixels are needed to represent the successively smaller areas.