Authoritative Answer

Specifies that the responding name server is an authority for the domain name in question section. Note that the contents of the answer section may have multiple owner names because of aliases. This bit corresponds to the name which matches the query name, or the first owner name in the answer section.

Advanced Audio Coding

Advanced Audio Coding (AAC) is a proprietary audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at the same bit rate. The confusingly named AAC+ (HE-AAC) does so only at low bit rates and less so at high ones.
 
AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4 specifications. Part of AAC, HE-AAC (AAC+), is part of MPEG-4 Audio and also adopted into digital radio standards DAB+ and Digital Radio Mondiale, as well as mobile television standards DVB-H and ATSC-M/H.
 
AAC supports inclusion of 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 16 low frequency effects (LFE, limited to 120 Hz) channels, up to 16 "coupling" or dialog channels, and up to 16 data streams. The quality for stereo is satisfactory to modest requirements at 96 kbit/s in joint stereo mode; however, hi-fi transparency demands data rates of at least 128 kbit/s (VBR). Tests of MPEG-4 audio have shown that AAC meets the requirements referred to as "transparent" for the ITU at 128 kbit/s for stereo, and 320 kbit/s for 5.1 audio.

An ATM Adaptation layer 1 or AAL1 is used for transmitting Class A network traffic, that is, real-time, constant bit rate, connection oriented traffic (example- uncompressed audio and video). Bits are fed in by the application at constant rate and must be delivered to other end with minimum delay, jitter or overhead. The input is stream of bits without message boundaries. For this traffic, error detection protocols cannot be used since timeouts and retransmission causes delay but the missing cells are reported to the application, that must take its own action to recover from them.

ATM Adaptation Layer 2

ATM Adaptation Layer 2 (AAL2) is an ATM adaptation layer for Asynchronous Transfer Mode (ATM), used primarily in telecommunications; for example, it is used for the Iu interfaces in the Universal Mobile Telecommunications System, and is also used for transporting digital voice. The standard specifications related to AAL2 are ITU standards I.363.2 and I366.1.
 
What is AAL2?
AAL2 is a variable bitrate, connection-oriented, low latency service originally intended to adapt voice for transmission over ATM. Like other ATM adaptation layers, AAL2 defines segmentation and reassembly of higher-layer packets into ATM cells, in this case packets of data containing voice and control information. AAL2 is further separated into two sub-layers that help with the mapping from upper layer services to ATM cells. These are named Service Specific Convergence Sub-layer (SSCS) and Common Part Sub-layer (CPS).

ATM Adaptation Layer 5

ATM Adaptation Layer 5 (AAL5) is an ATM adaptation layer used to send variable-length packets up to 65,535 octets in size across an Asynchronous Transfer Mode (ATM) network.
 
Unlike most network frames, which place control information in the header, AAL5 places control information in an 8-octet trailer at the end of the packet. The AAL5 trailer contains a 16-bit length field, a 32-bit cyclic redundancy check (CRC) and two 8-bit fields labeled UU and CPI that are currently unused.
 
Each AAL5 packet is divided into an integral number of ATM cells and reassembled into a packet before delivery to the receiving host. This process is known as Segmentation and Reassembly (see below). The last cell contains padding to ensure that the entire packet is a multiple of 48 octets long. The final cell contains up to 40 octets of data, followed by padding bytes and the 8-octet trailer. In other words, AAL5 places the trailer in the last 8 octets of the final cell where it can be found without knowing the length of the packet; the final cell is identified by a bit in the ATM header (see below), and the trailer is always in the last 8 octets of that cell.

Acceptance Test

Formal test defining acceptance criteria for a release.

An acceptance test is a formal description of the behavior of a software product, generally expressed as an example or a usage scenario. A number of different notations and approaches have been proposed for such examples or scenarios. In many cases the aim is that it should be possible to automate the execution of such tests by a software tool, either ad-hoc to the development team or off the shelf.

Activity

An element of work performed during a project, normally associated with an expected resource usage. The terms activities and tasks are somewhat interchangeable, although the PMBOK defines tasks as resulting from the breakdown of activities.

Activity Model

Specifies work or workflow by showing and describing the states and flow of control of the system or process.

Active Directory

Active Directory (AD) is a directory service that Microsoft developed for the Windows domain networks. It is included in most Windows Server operating systems as a set of processes and services. Initially, Active Directory was only in charge of centralized domain management. Starting with Windows Server 2008, however, Active Directory became an umbrella title for a broad range of directory-based identity-related services.
 
A server running Active Directory Domain Services (AD DS) is called a domain controller. It authenticates and authorizes all users and computers in a Windows domain type network—assigning and enforcing security policies for all computers and installing or updating software. For example, when a user logs into a computer that is part of a Windows domain, Active Directory checks the submitted password and determines whether the user is a system administrator or normal user. Also, it allows management and storage of information, provides authentication and authorization mechanisms, and establishes a framework to deploy other related services: Certificate Services, Federated Services, Lightweight Directory Services and Rights Management Services.
 
Active Directory uses Lightweight Directory Access Protocol (LDAP) versions 2 and 3, Microsoft's version of Kerberos, and DNS.

Ad Hoc Testing

See informal testing.

Ada

Ada is a structured, statically typed, imperative, and object-oriented high-level computer programming language, extended from Pascal and other languages. It has built-in language support for design-by-contract, extremely strong typing, explicit concurrency, tasks, synchronous message passing, protected objects, and non-determinism. Ada improves code safety and maintainability by using the compiler to find errors in favor of runtime errors. Ada is an international standard; the current version (known as Ada 2012) is defined by ISO/IEC 8652:2012.

Asymmetric Digital Subscriber Loop

AES

Advanced Encryption Standard

Agent

In a project charter, responsible for initiating, sponsoring, and supporting the project. Also see project sponsor.

a project management approach based on delivering requirements iteratively and incrementally throughout the life cycle.

an umbrella term specifically for iterative software development methodologies. Popular methods include Scrum, Lean, DSDM and eXtreme Programming (XP).

Describes the four principles of agile development:

1. Individuals and interactions over processes and tools.
2. Working software over comprehensive documentation.
3. Customer collaboration over contract negotiation.
   Responding to change over following a plan.

Alarm Indication Signaling

Alarm indication signal (AIS) (also called "all ones" because of the data and framing pattern) is a signal transmitted by an intermediate element of a multi-node transport circuit that is part of a concatenated telecommunications system to alert the receiving end of the circuit that a segment of the end-to-end link has failed at a logical or physical level, even if the system it is directly connected to is still working. The AIS replaces the failed data, allowing the higher order system in the concatenation to maintain its transmission framing integrity. Downstream intermediate elements of the transport circuit propagate the AIS onwards to the destination element.

An A-law algorithm is a standard companding algorithm, used in European 8-bit PCM digital communications systems to optimize, i.e. modify, the dynamic range of an analog signal for digitizing. It is one of two versions of the G.711 standard from ITU-T, the other version being the similar µ-law, used in North America and Japan.

Access Link Control Application Protocol

Control plane protocol for the transport layer in 3rd Generation UMTS networks is called ALCAP ("Access Link Control Application Part"). ALCAP is defined by 3GPP as equivalent of ITU recommendation Q.2630.2. Basic functionality of ALCAP is multiplexing of different users onto one AAL2 transmission path using channel IDs (CIDs). It is used in the UMTS access network UTRAN along with ATM, while IPBCP is use for IP links in the core of the network.
 
ALCAP makes it possible for up to 248 channels to be multiplexed onto one AAL2 bearer.
 

Amazon Electric Compute Cloud

Amazon Elastic Compute Cloud (EC2) forms a central part of Amazon.com's cloud-computing platform, Amazon Web Services (AWS), by allowing users to rent virtual computers on which to run their own computer applications. EC2 encourages scalable deployment of applications by providing a web service through which a user can boot an Amazon Machine Image (AMI) to configure a virtual machine, which Amazon calls an "instance", containing any software desired. A user can create, launch, and terminate server-instances as needed, paying by the second for active servers – hence the term "elastic". EC2 provides users with control over the geographical location of instances that allows for latency optimization and high levels of redundancy.

Asymmetric Multiprocessing

Adaptive Multi-Rate Narrow band

The Adaptive Multi-Rate (AMR, AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with toll quality speech starting at 7.4 kbit/s.
 
AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM[4] and UMTS. It uses link adaptation to select from one of eight different bit rates based on link conditions.

Adaptive Multi-Rate Wideband

Adaptive Multi-Rate Wideband (AMR-WB) is a patented wideband speech audio coding standard developed based on Adaptive Multi-Rate encoding, using similar methodology as algebraic code excited linear prediction (ACELP). AMR-WB provides improved speech quality due to a wider speech bandwidth of 50–7000 Hz compared to narrowband speech coders which in general are optimized for POTS wireline quality of 300–3400 Hz. AMR-WB was developed by Nokia and VoiceAge and it was first specified by 3GPP.
 
AMR-WB is codified as G.722.2, an ITU-T standard speech codec, formally known as Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB). G.722.2 AMR-WB is the same codec as the 3GPP AMR-WB. The corresponding 3GPP specifications are TS 26.190 for the speech codec and TS 26.194 for the Voice Activity Detector.
 
The AMR-WB format has the following parameters:

• Frequency bands processed: 50-6400 Hz (all modes) plus 6400-7000 Hz (23.85 kbit/s mode only)
• Delay frame size: 20 ms
• Look ahead: 5 ms
• AMR-WB codec employs a bandsplitting filter; the one-way delay of this filter is 0.9375 ms
• Complexity: 38 WMOPS, RAM 5.3KWords
• Voice activity detection, discontinuous transmission, comfort noise generator
• Fixed point: Bit-exact C
• Floating point: under work.

Analogy Estimation

Creating estimates by using expert judgment to compare proposed work to historical data for similar past work. Often coupled with fuzzy logic techniques.

Android is a mobile operating system developed by Google, based on a modified version of the Linux kernel and other open source software and designed primarily for touchscreen mobile devices such as smartphones and tablets. In addition, Google has further developed Android TV for televisions, Android Auto for cars, and Wear OS for wrist watches, each with a specialized user interface. Variants of Android are also used on game consoles, digital cameras, PCs and other electronics.

Access Network Discovery and Selection Function

American National Standards Institute

The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international standards so that American products can be used worldwide.
 
ANSI accredits standards that are developed by representatives of other standards organizations, government agencies, consumer groups, companies, and others. These standards ensure that the characteristics and performance of products are consistent, that people use the same definitions and terms, and that products are tested the same way. ANSI also accredits organizations that carry out product or personnel certification in accordance with requirements defined in international standards

are common solutions to common problems where the solution is ineffective and may result in undesired consequences.

aspect-oriented programming

In computing, aspect-oriented programming (AOP) is a programming paradigm that aims to increase modularity by allowing the separation of cross-cutting concerns. It does so by adding additional behavior to existing code (an advice) without modifying the code itself, instead separately specifying which code is modified via a "pointcut" specification, such as "log all function calls when the function's name begins with 'set'". This allows behaviors that are not central to the business logic (such as logging) to be added to a program without cluttering the code, core to the functionality. AOP forms a basis for aspect-oriented software development.
 
AOP includes programming methods and tools that support the modularization of concerns at the level of the source code, while "aspect-oriented software development" refers to a whole engineering discipline.
 
Aspect-oriented programming entails breaking down program logic into distinct parts (so-called concerns, cohesive areas of functionality). Nearly all programming paradigms support some level of grouping and encapsulation of concerns into separate, independent entities by providing abstractions (e.g., functions, procedures, modules, classes, methods) that can be used for implementing, abstracting and composing these concerns. Some concerns "cut across" multiple abstractions in a program, and defy these forms of implementation. These concerns are called cross-cutting concerns or horizontal concerns.
 
Logging exemplifies a crosscutting concern because a logging strategy necessarily affects every logged part of the system. Logging thereby crosscuts all logged classes and methods.
 
All AOP implementations have some crosscutting expressions that encapsulate each concern in one place. The difference between implementations lies in the power, safety, and usability of the constructs provided. For example, interceptors that specify the methods to intercept express a limited form of crosscutting, without much support for type-safety or debugging. AspectJ has a number of such expressions and encapsulates them in a special class, an aspect. For example, an aspect can alter the behavior of the base code (the non-aspect part of a program) by applying advice (additional behavior) at various join points (points in a program) specified in a quantification or query called a pointcut (that detects whether a given join point matches). An aspect can also make binary-compatible structural changes to other classes, like adding members or parents.

application programming interface

a specific method prescribed by a computer operating system or by an application program by which a programmer writing an application program can make requests of the operating system or another application.

Access Point Name

An Access Point Name (APN) is the name of a gateway between a GSM, GPRS, 3G or 4G mobile network and another computer network, frequently the public Internet.
 
A mobile device making a data connection must be configured with an APN to present to the carrier. The carrier will then examine this identifier to determine what type of network connection should be created, for example: which IP addresses should be assigned to the wireless device, which security methods should be used, and how or if, it should be connected to some private customer network.
 
More specifically, the APN identifies the packet data network (PDN) that a mobile data user wants to communicate with. In addition to identifying a PDN, an APN may also be used to define the type of service, (e.g. connection to Wireless Application Protocol (WAP) server, Multimedia Messaging Service (MMS)) that is provided by the PDN. APN is used in 3GPP data access networks, e.g. General Packet Radio Service (GPRS), evolved packet core (EPC).

Architecture

Top level overview and plan for a software system. See CxStand_Design for more information.

Artifact

The tangible result of work performed.
May be used at any level of detail, e.g., the artifact resulting from a task might be a document, while the artifact resulting from a project might be a software system.

ASCII, abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Most modern character-encoding schemes are based on ASCII, although they support many additional characters.
 
ASCII is the traditional name for the encoding system; the Internet Assigned Numbers Authority (IANA) prefers the updated name US-ASCII, which clarifies that this system was developed in the US and based on the typographical symbols predominantly in use there.

Abstract Syntax Notation One (ASN.1) is an interface description language for defining data structures that can be serialized and deserialized in a standard, cross-platform way. It is broadly used in telecommunications and computer networking, and especially in cryptography.
 
Protocol developers define data structures in ASN.1 modules, which are generally a section of a broader standards document written in the ASN.1 language. Because the language is both human-readable and machine-readable, modules can be automatically turned into libraries that process their data structures, using an ASN.1 compiler.
 
ASN.1 is similar in purpose and use to protocol buffers and Apache Thrift, which are also interface description languages for cross-platform data serialization. Like those languages, it has a schema (in ASN.1, called a "module"), and a set of encodings, typically type-length-value encodings. However, ASN.1, defined in 1984, predates them by many years. It also includes a wider variety of basic data types, some of which are obsolete, and has more options for extensibility. A single ASN.1 message can include data from multiple modules defined in multiple standards, even standards defined years apart.
 
FooProtocol DEFINITIONS ::= BEGIN
 
FooQuestion ::= SEQUENCE {
trackingNumber INTEGER(0..199),
question IA5String
}
 
FooAnswer ::= SEQUENCE {
questionNumber INTEGER(10..20),
answer BOOLEAN
}
 
FooHistory ::= SEQUENCE {
questions SEQUENCE(SIZE(0..10)) OF FooQuestion,
answers SEQUENCE(SIZE(1..10)) OF FooAnswer,
anArray SEQUENCE(SIZE(100)) OF INTEGER(0..1000),
...
}
 
END

Assessment

A review of the state or practices of a project or organization, often performed by an independent entity.

Acceptance Test Driven Development

involves team members with different perspectives (customer, development, testing) collaborating to write acceptance tests in advance of implementing the corresponding functionality.

Asynchronous Transfer Mode

Audit

Sometimes used as a synonym for assessment, usually in a more formal and independent context.

Author

For a review, the person assigned to represent the author viewpoint for an artifact. The author is normally the primary contributor to the creation of the artifact.

Authority

Responsible for funding and championing a project, the project sponsor.

In the context of software development, build refers to the process that converts files and other assets under the developers' responsibility into a software product in its final or consumable form. The build is automated when these steps are repeatable, require no direct human intervention, and can be performed at any time with no information other than what is stored in the source code control repository.

Automated Testing

The use of tools and technology to encode, execute, and note results of test cases on a system without human intervention.

AWK is a programming language designed for text processing and typically used as a data extraction and reporting tool. It is a standard feature of most Unix-like operating systems.
 
The AWK language is a data-driven scripting language consisting of a set of actions to be taken against streams of textual data – either run directly on files or used as part of a pipeline – for purposes of extracting or transforming text, such as producing formatted reports. The language extensively uses the string datatype, associative arrays (that is, arrays indexed by key strings), and regular expressions. While AWK has a limited intended application domain and was especially designed to support one-liner programs, the language is Turing-complete, and even the early Bell Labs users of AWK often wrote well-structured large AWK programs.

Amazon Web Services

Amazon Web Services (AWS) is a subsidiary of Amazon.com that provides on-demand cloud computing platforms to individuals, companies and governments, on a paid subscription basis. The technology allows subscribers to have at their disposal a virtual cluster of computers, available all the time, through the Internet. AWS's version of virtual computers emulate most of the attributes of a real computer including hardware (CPU(s) & GPU(s) for processing, local/RAM memory, hard-disk/SSD storage); a choice of operating systems; networking; and pre-loaded application software such as web servers, databases, CRM, etc. Each AWS system also virtualizes its console I/O (keyboard, display, and mouse), allowing AWS subscribers to connect to their AWS system using a modern browser. The browser acts as a window into the virtual computer, letting subscribers log-in, configure and use their virtual systems just as they would a real physical computer. They can choose to deploy their AWS systems to provide internet-based services for themselves and their customers.
 
The AWS technology is implemented at server farms throughout the world, and maintained by the Amazon subsidiary. Fees are based on a combination of usage, the hardware/OS/software/networking features chosen by the subscriber, required availability, redundancy, security, and service options. Subscribers can pay for a single virtual AWS computer, a dedicated physical computer, or clusters of either. As part of the subscription agreement, Amazon provides security for subscribers' system. AWS operates from many global geographical regions including 6 in North America.

Microsoft Azure is a cloud computing service created by Microsoft for building, testing, deploying, and managing applications and services through a global network of Microsoft-managed data centers. It provides software as a service (SaaS), platform as a service (PaaS) and infrastructure as a service (IaaS) and supports many different programming languages, tools and frameworks, including both Microsoft-specific and third-party software and systems.