.profile
A hidden file that contains shell commands. If you use the Bourne or Korn shell, this file runs automatically every time you log in.

P2P
Person to Person. A range of desktop conferencing products from IBM - . /P2P

packet
A quantum unit of network data. A packet's contents are generally a header portion (with content and routing information) and a data portion (with the actual data).

Packet Switching
A type of data transmission in which data is divided into packets, each of which has a destination address. Each packet is then routed across a network in an optimal fashion. An addressed packet may travel a different route than packets related to it. Packet sequence numbers are used at the destination node to reassemble related packets.

Packet
The basic division of data sent over a network. Each packet contains a set amount of data along with a header, containing information about the type of packet and the network address to which it is being sent. The size and format of packets depends on the protocol and frame types used.

Packets
A unit of information transmitted as a whole from one device to another on a network.

PACS
Public Access Computer Systems.

PAD
Packet Assembler and Disassembler: A PAD assembles packets of asynchronous data and emits these buffers in a burst to a packet switch network. The PAD also disassembles packets from the network and emits the data to the non-packet device.

PAGE -
A web page is not comparable to a real page of printed material, such as a brochure or a page from this document. Web pages can be nearly any length, although for practical reasons most people limit them to less than 400 lines of 80 column text or less. A Web Page is a computer file written in the Hyper Text Markup Language (HTML).

Page Description Language
A language such as Adobe PostScript PostScript or Xerox Interpress Interpress which allow the appearance of a printed page to be described in a high-level device-independent way. Printing then becomes a two-stage process: an application produces a description in the language, which is then interpreted by a specific output device. Such a language can serve as an interchange standard for transmission and storage of printable documents

Panda
An Internet navigation and information retrieval system from the University of Iowa -

Pansophic
A Software Engineering company in the US.

PAP:
Push Accesss Protocol(see also under WAP).

PARADIGM PLUS
A configurable object-oriented CASE tool from Proto Soft Inc. - .

Parallelogram
A deviation from true perpendicular of vertical or horizontal from each other.

parameter
A variable sent to a function when it is called, also known as an argument.

PaRC
A workstation cluster for engineering computing at CERN

PARC
See Xerox PARC Xerox-PARC.

parent directory
The directory that contains the current working directory. That is the current working directory is a subdirectory of the parent directory.

Parent Node
The logical group node that represents the containing peer group of a specific node at the next higher level of the hierarchy.

Parent Peer Group
The parent peer group of a peer group is the one containing the logical group node representing that peer group. The parent peer group of a node is the one containing the parent node of that node.

Parlog++
An object-oriented extension to MacParlog. It combines object-oriented object-oriented and parallel logic programming logic-programming, giving the benefits of both paradigms within a single coherent development environment.

Parser
A function that recognizes valid sentences of a language by analysing the syntax structure of a set of tokens tokenspassed to it from a lexical analyzer.

partition
A portion of a disk.

Pascal
A programming language designed by N.Wirth for teaching purposes, emphasising structured programming constructs, data structures and strong typing.

password
A secret blend of herbs and spices..no! A secret series of characters known only to you. You ype your password when you log in.

PATCHY
A FORTRAN code management code-managementprogram written at CERN /.

Path Constraint
A bound on the combined value of a topology metric along a path for a specific connection.

pathname
Instructions for how to get to a file. An absolute pathname tells you how to find a file beginning at the root directory and working down the tree. A relative pathname tells you how to find the file starting where you are now.

Pathologically Eclectic Rubbish Lister (PERL)
A programming scripting language used heavily in systems administration and web programming with the Common Gateway Interface (CGI) /c.

Pattern
A formal way to describe a solution to a commonly recurring programming problem - . /Pattern

PAW
Physics Analysis Workbench - general purpose portable tool for analysis and presentation of physics data

PAW++
An extended version of PAW PAW with a Motif Motifhuman interface.

payload
The 48-byte data portion of an ATM /a cell /c.

PBX
Private Branch eXchange: PBX is the term given to a device which provides private local voice switching and voice-related services within the private network. A PBX could have an ATM API to utilize ATM services, for example Circuit Emulation Service.

PBX
See Private Branch eXchange (PBX) /.

PC
A personal computer, usually one running DOS. As a Unix user, you now can sneer at PCs as "just toys." Now you have a "real computer." Ha! A pc can be used also to act as a terminal so that you can use a computer running Unix.(one of the authors is doing that at this very moment.) A big enough PC can run Unix on its own (that's what the other author is doing.)

PC
Personal Computer Personal-Computer.

PC
Protocol Control: Protocol Control is a mechanism which a given application protocol may employ to determine or control the performance and health of the application. Example, protocol liveness may require that protocol control information be sent at some minimum rate; some applications may become intolerable to users if they are unable to send at least at some minimum rate. For such applications, the concept of MCR is defined. Refer to MCR.

PC
See personal computer (PC) /.

PCA
A dynamic analyser from DEC giving information on run time performance and code utilisation.

P-CAD
A CAE CAE system marketed by CADAM, an IBM company.

PCL
Portable Common LOOPS LOOPS. A portable CLOS CLOS implementation.

PCL
Printer Control Language (from Hewlett Packard).

PCL
Printer control language, understood by a variety of printers made by Hewlett Packard.

PCM
Pulse Code Modulation: An audio encoding algorithm which encodes the amplitude of a repetitive series of audio samples. This encoding algorithm converts analog voice samples into a digital bit stream.

PCMCIA:
Personal Computer Memory Card International Association.

PCO
Point of Control and Observation: A place (point) within a testing environment where the occurrence of test events is to be controlled and observed as defined by the particular abstract test method used.

PCR
Peak Cell Rate: The Peak Cell Rate, in cells/sec, is the cell rate which the source may never exceed.

PCR
Program Clock Reference: A timestamp that is inserted by the MPEG-2 encoder into the Transport Stream to aid the decoder in the recovering and tracking the encoder clock.

PCTE
Portable Common Tool Environment: an ECMA ECMA standard framework for software tools developed in the Esprit Esprit programme. It is based on an entity-relationship Object Management System Object-Management-System and defines the way in which tools access this - . /PCTE

PCTE+
A European NATO specification based on PCTE PCTE with security enhancements.

PCX
A bitmap format from Zsoft - . /Graphics

PDA:
Personal Digital Assistant is the generic term used to describe a family of mobile devices offering users PIM functionality in the form of an electronic phone book, calendar and notepad.

PDC
See Primary Domain Controller (PDC) /.

PDDM
Product Data and Document Management.

PDF
Portable Document Format from Adobe Systems - . /PDF

PDH
Plesiochronous Digital Hierarchy: PDH (plesiochronous means nearly synchronous), was developed to carry digitized voice over twisted pair cabling more efficiently. This evolved into the North American, European, and Japanese Digital Hierarchies where only a discrete set of fixed rates is available, namely, nxDS0 (DS0 is a 64 kbps rate) and then the next levels in the respective multiplex hierarchies.

PDL
Page Description Language Page-Description-Language.

PDL
Program Design Language.

PDM
Product Data Management. An integrated system for managing all types of technical data concerning a product.

PDS
Planetary Data Systems format from - NASA. /Graphics

PDSA cycle
Plan, Do, See, Approve (from Japan).

PDU
Protocol Data Unit: A PDU is a message of a given protocol comprising payload and protocol-specific control information, typically contained in a header. PDUs pass over the protocol interfaces which exist between the layers of protocols (per OSI model).

Peer Entities
Entities within the same layer.

Peer Group
A set of logical nodes which are grouped for purposes of creating a routing hierarchy. PTSEs are exchanged among all members of the group.

Peer Group Identifier
A string of bits that is used to unambiguously identify a peer group.

Peer Group Leader
A node which has been elected to perform some of the functions associated with a logical group node.

Peer Group Level
The number of significant bits in the peer group identifier of a particular peer group.

Peer Node
A node that is a member of the same peer group as a given node.

Peer-to Peer Communication
A network computer that both shares resources with other computers and accesses the shared resources of other computers.

Peer-to Peer Network
A local area network in which network resources are shared among workstations, without a file server.

PEM
Privacy Enhanced Mail. An Internet Internet standard (RFC RFC 1421-1424).

PEP
Protocol Extension Protocol. A proposed system to allow HTTP HTTP clients and servers to negotiate protocol extensions.

Perceptron
This term is sometimes used to refer to a single McCulloch-Pitts McCulloch-Pitts neuron, but may also refer to a network of neurons in which the output(s) of some neurons are connected through weighted connections to the input(s) of other neurons. The term multilayer perceptron specifically refers to a network composed of more than one layer of neurons, with some or all of the outputs of each layer connected to one or more of the inputs of another layer. The first layer is called the input layer, the last one is the output layer, and in between there may be one or more hidden layers.

peripheral
Something that lets the computer communicate with the outside world - mainly with you. The keyboard, screen, mouse, printer, and modem all are peripherals.

PERL -
Another commonly used programming language used to code server based web applications.

PERL
Perl is a popular programming language used for creating interactive websites.

Perl
Practical Extraction and Report Language. An interpreted scripting language for scanning text files, extracting information, and printing reports. It combines features of c c, sed /man?sed, awk awkand sh sh- . /Perl

PERL
See Pathologically Eclectic Rubbish Lister (PERL) /.

Permanent Virtual Circuit (PVC)
A virtual circuit in an ATM /a network that is always up when the switch is up. Used for signalling and routing information.

permissions
Whoever has permission to look at, change, and execute stuff in a file or directory.

Persistence
Phosphor characteristic consisting of the ability to emit light after excitation current of electron beam is removed.

personal computer (PC)
A machine compatible with the 8088/80x86 Intel microprocessor family. A machine capable of emulating the 8088/80x86 Intel microprocessor (such as the NEXTSTEP application SoftPC).

Personal Computer
A general-purpose single-user microcomputer designed to be operated by one person at a time.

PES
Packetized Elementary Stream: In MPEG-2, after the media stream has been digitized and compressed, it is formatted into packets before it is multiplexed into either a Program Stream or Transport Stream.

Petri net
A graphical representation of concurrent systems in terms of tokens, places and transition bars - . /Petri

PEX
(PHIGS PHIGS Extension to X) Extension to the X Window System X-Window-Systemproviding 3-D graphics support.

PG
Peer Group: A set of logical nodes which are grouped for purposes of creating a routing hierarchy. PTSEs are exchanged among all members of the group.

PGL
Peer Group Leader: A single real physical system which has been elected to perform some of the functions associated with a logical group node.

PGP
Pretty Good Privacy. A set of encryption tools for electronic mail etc. - . /PGP

PGP
See Pretty Good Privacy (PGP) /.

PHIGS
Programmers Hierarchical Interactive Graphics System: an ANSI/ISO standard.

Phosphor
Chemical compound that emits light while being excited by electrons.

PHY
OSI Physical Layer: The physical layer provides for transmission of cells over a physical medium connecting two ATM devices. This physical layer is comprised of two sublayers: the PMD Physical Medium Dependent sublayer, and the TC Transmission Convergence sublayer. Refer PMD and TC.

Physical Layer (PHY) Connection
An association established by the PHY between two or more ATM entities. A PHY connection consists of the concatenation of PHY links in order to provide an end-to-end transfer capability to PHY SAPs.

Physical Layer
The cables, connectors, and connection ports of a network. These are the passive physical components required to create a network.

Physical Link
A real link which attaches two switching systems.

PI:
Push Initiator (see also under WAP).

PICS
Platform for Internet Content Selection.

PICS
Protocol Implementation Conformance Statement: A statement made by the supplier of an implementation or system stating which capabilities have been implemented for a given protocol.

PID
Protocol Identification. Refer to OUI.

PID
See process ID (PID) /.

PII
Process Improvement Institute - . /PII.txt

PIM
Product Information Management. See PDM PDM

PIM:
Personal Information Manager.

Pincushion
An inward bowing of the video image. All monitors experience slight amount of pincushion distortion. The manufacturer has a guideline on what the specification is for each model. The pincushion changes per resolution and also according to the size of the image. Pincushion is similar to bowing or barrel distortion.

PING -
A command, which allows you to verify a connection from the machine, you are on, to another machine on the internet.

Ping (Packet internet Groper)
A packet used to test reachability of destination by sending them an ICMP echo request and waiting for reply. The term is used as a verb: “Ping host A to see if it is up.”

PinK
PinK is not KUIP. An interface between Tcl /Tk , BLT, ADAMO and DAD from DESY -

pipe
The | character used to redirect the output of one command so that it becomes the input of another command.

PIXIT
Protocol Implementation eXtra Information for Testing: A statement made by a supplier or implementor of an IUT which contains information about the IUT and its testing environment which will enable a test laboratory to run an appropriate test suite against the IUT.

PKI:
Public Key Infrastructure.

Plastic Fiber Optics
An optical fiber where the core transmission media is plastic in contrast to glass or silica cores. Proposed plastic fibers generally have larger attenuation and dispersion than glass fiber but may have applications where the distance is limited. Plastic systems may also offer lower cost connectors that may be installed with simple tools and a limited amount of training.

platter
A single piece of magnetic or magnetic/optical media on which data is stored. Multiple platters make up a disk. See also cylinder /c, track /t.

PLCP
Physical Layer Convergence Protocol: The PLCP is defined by the IEEE 802.6. It is used for DS3 transmission of ATM. ATM cells are encapsulated in a 125microsecond frame defined by the PLCP which is defined inside the DS3 M-frame.

Plexus
A set of modular WWW server software written in Perl

PLL
Phase Lock Loop: Phase Lock Loop is a mechanism whereby timing information is transferred within a data stream and the receiver derives the signal element timing by locking its local clock source to the received timing information.

PM
Physical Medium: Physical Medium refers to the actual physical interfaces. Several interfaces are defined including STS-1, STS-3c, STS-12c, STM-1, STM-4, DS1, E1, DS2, E3, DS3, E4, FDDI-based, Fiber Channel-based, and STP. These range in speeds from 1.544Mbps through 622.08 Mbps.

PMD
Physical Media Dependent: This sublayer defines the parameters at the lowest level, such as speed of the bits on the media.

PMM
Process Maturity Model.

PNG
Portable Network Graphics. A standard for bitmapped image files

PNI
Permit Next Increase: An ABR service parameter, PNI is a flag controlling the increase of ACR upon reception of the next backward RM-cell. PNI=0 inhibits increase. The range is 0 or 1.

PNNI
Private Network-Network Interface: A routing information protocol that enables extremely scalable, full function, dynamic multi-vendor ATM switches to be integrated in the same network.

PNNI Protocol Entity
The body of software in a switching system that executes the PNNI protocol and provides the routing service.

PNNI Routing Control Channel
VCCs used for the exchange of PNNI routing protocol messages.

PNNI Routing Domain
A group of topologically contiguous systems which are running one instance of PNNI routing.

PNNI Routing Hierarchy
The hierarchy of peer groups used for PNNI routing.

PNNI Topology State Element
A collection of PNNI information that is flooded among all logical nodes within a peer group.

PNNI Topology State Packet
A type of PNNI Routing packet that is used for flooding PTSEs among logical nodes within a peer group.

POH
Path Overhead: A maintenance channel transmitted in the SONET overhead following the path from the beginning multiplexer to the ending demultiplexer. This is not implemented in SONET Lite.

Point to Point Protocol (PPP)
The successor protocol (RFC 1661) ftp://ftp.isi.edu/in-notes/rfc1661.txt to SLIP /s; PPP provides a point-to-point connection between individual entities using either a synchronous or an asynchronous data link. One of its primary features is the ability for one side to configure the IP /i address of the other side.

Point-to-Multipoint Connection
A Point-to-Multipoint Connection is a collection of associated ATM VC or VP links, with associated endpoint nodes, with the following properties:

Note: UNI 4.0 does not support traffic sent from a Leaf to the Root.

Point-to-Point Connection
A connection with only two endpoints.

policy
A rule that an administrator places on the system, providing a way for an administrator to customize applications to organization-specific needs; policies are rules that govern the management of resources.

policy independence
A characterstic of the X window system in which windows can look and act any way the software developers want. This idea is the converse of the idea that, if all the windows on your screen look and act in a similar way, they will be easier for you to use.

policy region
Associates specific policies with instances of policy-driven object types in order to enforce the application of these policies to managed resources; a policy region is a collection of TME /t resources that are governed by a common set of policies /.

policy-driven object
An object /o for which policies / have been defined and whose behavior is determined by those policies.

Polling
The process by which a computer periodically ask each terminal or device on a LAN if it has message to send, and then allows each to send data in turn. On a multipoint connection or a point-to-point connection, polling is the process whereby data stations are invited one at a time to transmit.

Polymorphism
In object-oriented object-orientedprogramming, the term is used to describe variables which may refer at run-time to objects of different classes. For example, the variable "myVehicle" could refer to an object of class "motorCar" or "Truck".

POP
See Post Office Protocol (POP) /.

POP:
Post Office Protocol, a protocol used to retrieve e-mail from a web server.

Port Identifier
The identifier assigned by a logical node to represent the point of attachment of a link to that node.

Portable Operating System Interface (POSIX)
A standard operating system interface that allows both Berkeley-based and AT&T-based Unix systems to share a common system call interface.

portable software
Software (programs) that can be run on a number of different kinds of computers. Unix is portable because it runs on an amazing number of different types of computers.

POSIX
Portable Operating System Interface for computer environments. A set of IEEE IEEE standards designed to provide application portability. IEEE1003.1 defines a UNIX UNIX-like operating system interface, 1003.2 the shell and utilities, and 1003.4 real-time real-time extensions.

POSIX
See Portable Operating System Interface (POSIX) /.

POSIX
The IEEE portable operating system interface. (Aren't you glad you asked?) POSIX defines a family of definitions of how parts of computer systems work with each other and incidentally, with users. POSIX is intended to look just like Unix but to be independent of any specific vendor. There are about a dozen members of the POSIX family; the one you care about is 1003.2 (known as "dot two") and the related user portability extension (UPE). Together, they define the way the commands and shells work. A system that compiles with 1003.2 and UPE looks enough like Unix that everything in this book applies to it.

POSS
Persistent Object Service Specification: an OMG OMG specification.

Post Office Protocol (POP)
A protocol (a precursor to Internet Mail Access Protocol (IMAP) /i) that defines how a client /c should fetch mail from and return mail to a mail server /s. Defined in RFC 937 (v2) ftp://ftp.isi.edu/in-notes/rfc937.txt and in RFC 1939 (v3) ftp://ftp.isi.edu/in-notes/rfc1939.txt.

POSTGRES
An active DBMS active-DBMS from Univ. of Calif. Berkeley.

postscript
A computer language spoken by printers and the programs that communicate with these printers. PostScript enables printers to print a wonderful array of characters in all kinds of sizes and shapes, as well as pictures. When a program wants to print something on a PostScript printer, rather than just send the characters to print, it has to send a PostScript program that tells the printer how to print the stuff.

Postscript
A page description language page-description-language from Adobe Systems Inc. Its primary application is to describe the appearance of text, graphical shapes and sampled images on printed or displayed pages. A program in PostScript can communicate a document description from a composition system to a printing system in a device-independent way. Many printers now interpret PostScript directly

Potential Browser
A computer on a network that a may maintain a list of other computers and services on the network if requested to do so by a Master browser.

PPG:
Push Proxy Gateway.

PPP -
Point to Point Protocol. PPP is a superset of the TCP/IP protocols. Built upon that foundation, but instead of allowing one computer to be able to talk to many, it relies on the fact that the other computer it's linked with has that ability and therefore does not need it.

PPP
Point to Point Protocol.

PPP
Point-to-Point Protocol. This protocol allows the sending of IP packets on a dial-up (serial) connection. Supports compression and IP Address negotiation.

PPP
See Point to Point Protocol (PPP) /.

PPP:
Point to Point Protocol, defined by the IETF. This protocol defines the means to transfer IP packets to and from a LAN.

PPTP
Point to Point Tunneling Protocol.

Pragma
A standardised form of kluge in Ada Ada.

Predicate calculus
A notation for representing logical statements which goes beyond propositional calculus in certain ways.

prefix
The network-specific portion of a CIDR /c address. The prefix identifies the network routing information, such as the network address or subnet information.

PREMO
Presentation Environment for Multimedia Objects. An ISO ISO standard under development for creation, presentation and interaction with information using single or multiple media

Presentation Layer
That layer of the OSI model that converts and translates (if necessary) information between the Session and Application layers.

Presentation Manager
The user interface to the OS/2 OS/2 system.

Pretty Good Privacy (PGP)
A public key/private key encryption scheme used to digitally sign messages, encrypt files, of both.

PRI
Primary Rate Interface: An ISDN standard for provisioning of 1.544 Mbit/s (DS1 - North America, Japan, et al) or 2.048 Mbit/s (E1 - Europe) ISDN services. DS1 is 23 "B" channels of 64 kbit/s each and one signalling "D" channel of 64 kbit/s/ E1 is 30 "B" channels of 64 kbit/s each and one signalling "D" channel of 64 kbit/s.

primary
A DNS /d server with local files; like an NIS /n master /m server.

Primary Domain Controller (PDC)
A Windows NT server containing the master copy of the account database for a domain. Changes are written to the PDC before being replicated to the Backup Domain Controllers (BDC) /b in the domain.

Primary Domain Controller (PDC) The domain server that contains the master copy of the security, computer, and user accounts databases and that can authenticate workstation. The primary domain controller can replicate its databases to one or more backup domain controllers and is usually also the Master browser for the domain.

Primitive
An abstract, implementation independent, interaction between a layer service user and a layer service provider.

principal
The name of a service, administrator or user registered in a security database such as Kerberos /k, in order to give that name various access privileges.

principle
(Security.) High-level fundamentals.

printer
A machine that marks on paper, preferably representing the letters or pictures you requested. There are many kinds of printers. The printer may be connected to your computer; if you are on a network, it may be connected to a computer elsewhere in your office. To find it, just listen for the sound of printing or follow people around for a while.

Private ATM Address
A twenty-byte address used to identify an ATM connection termination point.

Private Branch eXchange (PBX)
A telephone switch local to and belonging to an organization other than a carrier. See also Public Switched Telephone Network (PSTN) /.

privilege
The level of security required to access an object /o.

procedure
(Security.) Details on how to achieve various highly-sensitive tasks.

process
A running program.

process ID (PID)
The unique identifier for a process in the system process table.

Process/Application Layer
The upper layer in the DoD model that refers to the Application, Presentation, and Session Layers of the OSI model.

ProDoc
A set of tools for software documentation from SPC SPC

profile
Configuration information that describes a certain capability or setup; a prototype for configuration information or properties that are common to a group of machines or that apply to an application.

Profile:
is basically a schema that encapsulates the display or network.

Project assurance
The process of specifying the support system: techniques, internal standards, measurements, tools, and training for a project; counseling the project team in the application of these elements and monitoring the adherence to the standards.

Project management
The process of planning, organizing, staffing, directing, and controlling the production of a system. Software tools are available to help with this - . /proj-plan/faq

Project planning
See Project management project-management.

PROLOG
A language for PROgramming in LOGic.

Prometheus
A high-level programming language designed for logic, mathematics, and artificial intelligence. It contains elements from C, Pascal, LISP and Prolog plus novel features -

prompt
The character or characters displayed whenever Unix (or some other program) is waiting for you to type something. The two common Unix prompts are $ (if you use the Bournre or korn shell ) or % (if you use the C shell).

property
A variable that is stored as part of an object. Each object can have any number of properties.

Propositional calculus
A system of symbolic logic.

PROST
Programme for Research in Open Systems Testing of the DTI DTI

protection domain
Describes the bounds of an operation and the data that needs to be serialized or protected from other threads of execution.

Protocol
A set of rules and formats (semantic and syntactic) that determines the communication behavior of layer entities in the performance of the layer functions.

Protocol
An agreement about how to transmit data, especially across networks. Low level protocols define the electrical and physical standards to be observed, and deal with the transmission and error detection and correction of the bit stream. High level protocols deal with the data formatting, including the form of messages, the terminal to computer dialogue, files, etc.

Protocol Control Information
Information exchanged between corresponding entities, using a lower layer connection, to coordinate their joint operation.

Protocol Suite
A collection of protocols that are associated with and that implement a particular communication model (such as the networking model, or the OSI reference model).

protocol
The control information used to establish a procedure for transmitting data between peer entities; protocols describe the form in which data will be transmitted, the method to keep sending and receiving units synchronized, and how the data will be checked for errors.

PROTOCOL
The must follow regulations that govern the transmission and receipt of information across a data communications link.Languages that computers use to talk to each other.A set of standards that assures that different network products can work together.Any product using a given protocol should work with any other product using the same protocol.

Prototyper
An interface builder for the Macintosh from Smethers Barnes .

Prototyping
The creation of a model and the simulation of all aspects of a product. CASE tools CASE-tools support different degrees of prototyping. Some offer the end-user the ability to review all aspects of the user interface and the structure of documentation and reports before code is generated.

PRS
Primary Reference Source

prune
Remove unnecessary or unused branches from a multicast /m router (mrouter /m) network when no sites on those branches are part of a multipoint call.

PS
PostScript PostScript.

PSA
Problem Statement Analyzer: see PSL/PSA PSL/PSA.

Pseudocode
A notation resembling a programming language but not intended for actual compilation. It usually combines some of the structure of a programming language with an informal natural-language description of the computations to be carried out. It is often produced by CASE CASE systems as a basis for later hand coding.

PSL
Problem Statement Language: see PSL/PSA PSL/PSA.

PSL
Problem Statement Language: see PSL/PSA PSL/PSA.

PSL/PSA
Problem Statement Language/Problem Statement Analyser: a CASE CASE system developed by D.Teichroew. It allows computer-based development and analysis of a statement of requirements, and assistance during the design phase.

PSP
Personal Software Process. Methods to improve the quality of work of individual software engineers - . /PSP

PSTN
See Public Switched Telephone Network (PSTN) /.

PT
Payload Type: Payload Type is a 3-bit field in the ATM cell header that discriminates between a cell carrying management information or one which is carrying user information.

PTI Payload
Type Indicator: Payload Type Indicator is the Payload Type field value distinguishing the various management cells and user cells. Example: Resource Management cell has PTI=110, end-to-end OAM F5 Flow cell has PTI=101.

PTI
Portable Tool Interface: a standard such as PCTE PCTE, allowing interworking between different software tools via defined interfaces to the user and to the repository or object management system.

PTMPT
Point-To-Multipoint: A main source to many destination connections.

PTR
record See DNS record types, PTR record /d.

PTS
Presentation Time Stamp: A timestamp that is inserted by the MPEG-2 encoder into the packetized elementary stream to allow the decoder to synchronize different elementary streams (i.e. lip sync).

PTSE
PNNI Topology State Element: A collection of PNNI information that is flooded among all logical nodes within a peer group.

PTSP
PNNI Topology State Packet: A type of PNNI Routing packet that is used for flooding PTSEs among logical nodes within a peer group.

Public Switched Telephone Network (PSTN)
A global network of interconnected digital and analog communication links originally designed to support voice communication between any two points in the world. It was quickly adapted to handle digital data traffic when the in the world. It was quickly adapted to handle digital data traffic when the computer revolution occurred. In addition to its voice support role, the PSTN now functions as the Physical layer of the Internet by providing dial-up and leased lines for private and public use.

Public Switched Telephone Network (PSTN)
The network of telephone switches and other hardware belonging to a telephone company.

PureLink
An incremental linker from Pure Software - . /Pure

Purify
A debugging tool from Pure Software - . /Pure

Purity
The ability of the electron beam to lit precisely the correct phosphor color dot. If a full page of red color is shown on the display, impurity would result in a purple or greenish color region. This impurity can occur if the shadow mask has been damaged or if the screen has become magnetized. Degaussing the screen may fix the problem.

PURL
Persistent URL URL. Instead of pointing directly to the location of an Internet Internet resource, a PURL points to a resolution service that associates the PURL with the actual URL and returns that URL to the client. See the OCLC PURL Service.

Push Message:
is a message from a PI, which is pushed to one or more (Multicast Message) clients.

pushpin
A cute, little gizmo in the upper left corner of an OPEN LOOK window. If you push in the pushpin, it pins the window so that it stays open. Cute, no?

PV~WAVE
Interactive scientific visualisation software from Visual Numerics - .

PVC
Permanent Virtual Circuit: This is a link with static route defined in advance, usually by manual setup.

PVC
See Permanent Virtual Circuit (PVC) /.

PVCC
Permanent Virtual Channel Connection: A Virtual Channel Connection (VCC) is an ATM connection where switching is performed on the VPI/VCI fields of each cell. A Permanent VCC is one which is provisioned through some network management function and left up indefinitely.

PVPC
Permanent Virtual Path Connection: A Virtual Path Connection (VPC) is an ATM connection where switching is performed on the VPI field only of each cell. A Permanent VPC is one which is provisioned through some network management function and left up indefinitely.