What is

A#

<language> /A sharp/ A separable component of Version 2 of the AXIOM* computer algebra system. It provides a programming language with an optimising compiler, an intermediate code interpreter, and a library of data structures and mathematical abstractions. The compiler produces stand-alone executable programs, object libraries in native operating system formats, portable bytecode libraries, C and Lispsource code.

The A# programming language has support for object-oriented and functional programming styles. Both types and functions are first class values that can be manipulated with a range of flexible and composable primitives and user programs. The A# language design places particular emphasis on compilation for efficient machine code and portability.

Ports have been made to various 16, 32, and 64 bit architectures: RS/6000, SPARC, DEC Alpha, i386, i286, Motorola 680x0, S 370; several operating systems: Linux, AIX, SunOS, HP/UX, Next, Machand other Unix systems, OS/2, DOS, Microsoft Windows, VMS and CMS; C compilers: Xlc, gcc, Sun, Borland, Metaware and MIPS C.

A# is a separable component of Version 2 of the

_______________ computer algebra system.

optimising compiler

intermediate code interpreter

mathematical abstrasctions

stand-alone executable programs

object libraries

native operating system formats

portable bytecode libraries

C and Lispsource code

object-oriented

functional 

What is

A-0

What is

a1

<language> Address 1 code.

An a1 code interpreter, by Matthew Newhook <matthew@engr.mun.ca> was used to test compiler output. It requires gcc 2.4.2 or higher and is portable to computers with memory segment protection.

ftp://ftp.cs.mun.ca/pub/a1.

What is

A1 security

Orange Book

<security, standard> A standard from the US Government National Computer Security Council (an arm of the U.S. National Security Agency), "Trusted Computer System Evaluation Criteria, DOD standard 5200.28-STD, December 1985" which defines criteria for trusted computer products. There are four levels, A, B, C, and D. Each level adds more features and requirements.

D is a non-secure system.

C1 requires user log-on, but allows group ID.

C2 requires individual log-on with password and an audit mechanism. (Most Unix implementations are roughly C1, and can be upgraded to about C2 without excessive pain).

Levels B and A provide mandatory control. Access is based on standard Department of Defense clearances.

B1 requires DOD clearance levels.

B2 guarantees the path between the user and the security system and provides assurances that the system can be tested and clearances cannot be downgraded.

B3 requires that the system is characterised by a mathematical model that must be viable.

A1 requires a system characterized by a mathematical model that can be proven.

See also crayola books, book titles.

What is the

A20 handler

What is

A-3

ARITH-MATIC

<language> An extension of Grace Hopper's A-2 programming language, developed in about 1955. ARITH-MATIC was originally known as A-3, but was renamed by the marketing department ofRemington Rand UNIVAC.

http://cispom.boisestate.edu/cis221emaxson/hophtm.htm.

What is

A3D

<hardware> (Aureal 3-Dimensional?) A technology developed by Aureal that delivers sound with a three-dimensional effect through two speakers. Many modern sound cards and PC games now support this feature.

A3D differs from the various forms of surround sound in that it only requires two speakers, while surround sound typically requires four or five. It is sometimes less convincing than surround sound but is supposedly better in interactive environments. For example, PC games in which sounds often move from one speaker to another favour A3D, while pre-recorded video favours surround sound.

http://a3d.com/.

What is

A4C

What is

a56

What is

AAC

Advanced Audio Coding

<audio> (AAC) A successor to MP3, allowing lower bit rates and more stable quality.

What is

AADL

Axiomatic Architecture Description Language

<language, architecture, parallel> (AADL) A language allowing concise modular specification of multiprocessor architectures from the compiler/operating-system interface level down to chip level. AADL is rich enough to specify target architectures while providing a concise model for clocked microarchitectures.

["AADL: A Net-Based Specification Method for Computer Architecture Design", W. Damm et al in Languages for Parallel Architectures, J.W. deBakker ed, Wiley, 1989].

What is

AAL

What is

AAP

Association of American Publishers

<body, publication> <body> (AAP) A group engaged in standardisation efforts in document preparation.

What is

AAP DTD

AAP DTD (Association of American Publishers - Document Type Definition)

<standard> A DTD for a standard SGML document type for scientific documents, defined by the Association of American Publishers.

What is

aard

<programming, tool> (Dutch for "earth") A tool to check memory use for C++ programs, written by Steve Reiss <spr@cs.brown.edu> (who names his programs after living systems).

Aard tracks the state of each byte of memory in the heap and the stack. The state can be one of Undefined, Uninitialised, Free or Set. The program can detect invalid transitions (i.e. attempting to set or use undefined or free storage or attempting to access uninitialised storage).

In addition, the program keeps track of heap use through malloc and free and at the end of the run reports memory blocks that were not freed and that are not accessible (i.e. memory leaks).

The tools works using a spliced-in shared library on SPARCs running C++ 3.0.1 under SunOS 4.X.

ftp://wilma.cs.brown.edu/pub/aard.tar.Z.

What is

AARP

Apple Address Resolution Protocol

<networking> (AARP) Apple's system to allow AppleTalk protocol to work over networks other than LocalTalk, such as Ethernet or Token Ring. AppleTalk nodes announce their presence to the network so that other nodes can address messages to them. AARP maps between AppleTalk addresses and other schemes. It is actually a general address mapping protocol that can be used to map between addresses at any protocol level.

[G. Sidhu, R. Andrews, and A. Oppenheimer, "Inside AppleTalk", Addison Wesley, 1990].

What are

AARP probe packets

What is

AAUI

Apple Attachment Unit Interface

<hardware, networking> (AAUI) A 14-position, 0.050-inch-spaced ribbon contact connector. Early Power Macs and Quadras had an AAUI (Apple Attachment Unit Interface) port (rectangular shaped) for Ethernet, which requires a transceiver. To use twisted pair cabling, you would need to get a twisted pair transceiver for the computer with an AAUI port. Some Power Mac computers had both an AAUI and RJ-45 port; you can use one or the other, but not both.

The pin-out is:

  Pin   Signal Name     Signal Description
  ----  --------------  ---------------------------------
  1     FN Pwr          Power (+12V @ 2.1W or +5V @ 1.9W)
  2     DI-A            Data In circuit A
  3     DI-B            Data In circuit B
  4     VCC             Voltage Common
  5     CI-A            Control In circuit A
  6     CI-B            Control In circuit B
  7     +5V             +5 volts (from host)
  8     +5V             Secondary +5 volts (from host)
  9     DO-A            Data Out circuit A
  10    DO-B            Data Out circuit B
  11    VCC             Secondary Voltage Common
  12    NC              Reserved
  13    NC              Reserved
  14    FN Pwr          Secondary +12V @ 2.1W or +5V @ 1.9W
  Shell Protective Gnd  Protective Ground

AAUI signals have the same description, function, and electrical requirements as the AUI signals of the same name, as detailed in IEEE 802.3-1990 CSMA/CD Standard, section 7.

What is

A&B

What is

abbrev

What is the

Abbreviated Test Language for Avionics Systems

<language> (ATLAS) A Mil-spec language for automatic testing of avionics equipment. ATLAS replaced Gaelic and several other test languages.

["IEEE Standard ATLAS Test Language", IEEE Std 416-1976].

What is

ABC

1. <computer> Atanasoff-Berry Computer.

2. <language> An imperative language and programming environment from CWI, Netherlands. It is interactive, structured, high-level, and easy to learn and use. It is a general-purpose language which you might use instead of BASIC, Pascal or AWK. It is not a systems-programming language but is good for teaching or prototyping.

ABC has only five data types that can easily be combined; strong typing, yet without declarations; data limited only by memory; refinements to support top-down programming; nesting by indentation. Programs are typically around a quarter the size of the equivalent Pascal or C program, and more readable.

ABC includes a programming environment with syntax-directed editing, suggestions, persistent variables and multiple workspaces and infinite precision arithmetic.

An example function words to collect the set of all words in a document:

   HOW TO RETURN words document:
      PUT {} IN collection
      FOR line in document:
         FOR word IN split line:
            IF word not.in collection:
               INSERT word IN collection
      RETURN collection

Interpreter/compiler, version 1.04.01, by Leo Geurts, Lambert Meertens, Steven Pemberton <Steven.Pemberton@cwi.nl>. ABC has been ported to Unix, MS-DOS, Atari, Macintosh.

http://cwi.nl/cwi/projects/abc.html.

FTP eu.net, FTP nluug.nl, FTP uunet.

Mailing list: <abc-list-request@cwi.nl>.

E-mail: <abc@cwi.nl>.

["The ABC Programmer's Handbook" by Leo Geurts, Lambert Meertens and Steven Pemberton, published by Prentice-Hall (ISBN 0-13-000027-2)].

["An Alternative Simple Language and Environment for PCs" by Steven Pemberton, IEEE Software, Vol. 4, No. 1, January 1987, pp. 56-64.]

(1995-02-09)

2. <language> Argument, Basic value, C?.

An abstract machine for implementation of functional languages and its intermediate code.

[P. Koopman, "Functional Programs as Executable Specifications", 1990].

What is

ABC ALGOL

<language> An extension of ALGOL 60 with arbitrary data structures and user-defined operators, for symbolic mathematics.

["ABC ALGOL, A Portable Language for Formula Manipulation Systems", R.P. van de Riet, Amsterdam Math Centrum 1973].

What is

ABCL/1

<language> An Object-Based Concurrent Language.

The language for the ABCL MIMD system, written by Akinori Yonezawa <matsu@is.s.u-tokyo.ac.jp> of Department of Information Science, Tokyo University in 1986. ABCL/1 uses asynchronousmessage passing to objects. It requires Common Lisp. Implementations in KCL and Symbolics Lisp are available from the author.

ftp://camille.is.s.u-tokyo.ac.jp/.

E-mail: <abcl@is.s.u-tokyo.ac.jp>.

["ABCL: An Object-Oriented Concurrent System", A. Yonezawa ed, MIT Press 1990]. (1990-05-23).

What is

ABCL/c+

<language> A concurrent object-oriented language, an extension of ABCL/1 based on C.

["An Implementation of An Operating System Kernel using Concurrent Object Oriented Language ABCL/c+", N. Doi et al in ECOOP '88, S. Gjessing et al eds, LNCS 322, Springer 1988].

<language> A reflective subset of ABCL/1, written in ABCL/1 by Yonezawa of Tokyo Institute of Technology in 1988.

ftp://camille.is.s.u-tokyo.ac.jp/pub/abclr.

["Reflection in an Object-Oriented Concurrent Language", T. Watanabe et al, SIGPLAN Notices 23(11):306-315 (Nov 1988)].

What is

ABCL/R2

<language> An object-oriented, concurrent, reflective language based on Hybrid Group Architecture. ABCL/R2 was produced by <masuhara@is.s.u-tokyo.ac.jp>, <matsu@is.s.u-tokyo.ac.jp>,<takuo@is.s.u-tokyo.ac.jp>, <yonezawa@is.s.u-tokyo.ac.jp>, at the Tokyo Institute of Technology in 1992.

As a reflective language, an ABCL/R2 program can dynamically control its own behaviour, such as scheduling policy, from within a user-program. This system has almost all functions of ABCL/1 and is written in Common Lisp.

ftp://camille.is.s.u-tokyo.ac.jp/pub/abclr2/.

What is

abduction

<logic> The process of inference to the best explanation.

"Abduction" is sometimes used to mean just the generation of hypotheses to explain observations or conclusionsm, but the former definition is more common both in philosophy and computing.

The semantics and the implementation of abduction cannot be reduced to those for deduction, as explanation cannot be reduced to implication.

Applications include fault diagnosis, plan formation and default reasoning.

Negation as failure in logic programming can both be given an abductive interpretation and also can be used to implement abduction. The abductive semantics of negation as failure leads naturally to anargumentation-theoretic interpretation of default reasoning in general.

[Better explanation? Example?]

["Abductive Inference", John R. Josephson <jj@cis.ohio-state.edu>].

What is

ABEND

What is

AberMUD

What is

ABI

Application Binary Interface

<programming> (ABI) The interface by which an application program gains access to operating system and other services. It should be possible to run the same compiled binary applications on any system with the right ABI.

Examples are 88open's Binary Compatibility Standard, the PowerOpen Environment and Windows sockets.

What is

ABLE

<language> A simple language for accountants.

["ABLE, The Accounting Language, Programming and Reference Manual," Evansville Data Proc Center, Evansville, IN, Mar 1975].

[Listed in SIGPLAN Notices 13(11):56 (Nov 1978)].

What is

ABM

Asynchronous Balanced Mode

<protocol> A communication mode of HDLC and derivative protocols, supporting peer-oriented point-to-point communications between two nodes, where either node can initiate transmission.

What is

ABNF

Augmented Backus-Naur Form

<language> An extension of Backus-Naur Form documented in RFC 2234.

What does the term

' abort '

mean?

<programming> To terminate a program or process abnormally and usually suddenly, with or without diagnostic information. "My program aborted", "I aborted the transmission". The noun form in computing is "abort", not "abortion", e.g. "We've had three aborts over the last two days".

If a Unix kernel aborts it is known as a panic.

What is

ABP

1. <networking> Alternating bit protocol.

2. Microsoft Address Book Provider.

What is

ABR

What does the term

' abscissa '

mean?

<mathematics> The horizontal or x coordinate on an (x, y) graph; the input of a function against which the output is plotted.

The vertical or y coordinate is the "ordinate".

What is

ABSET

<language> An early declarative language from the University of Aberdeen.

["ABSET: A Programming Language Based on Sets", E.W. Elcock et al, Mach Intell 4, Edinburgh U Press, 1969, pp.467-492].

What does the term

' absolute path '

mean?

What is an

absolute pathname

What does the term

' abstract '

mean in computer terminology?

<philosophy> A description of a concept that leaves out some information or details in order to simplify it in some useful way.

Abstraction is a powerful technique that is applied in many areas of computing and elsewhere. For example: abstract class, data abstraction, abstract interpretation, abstract syntax, Hardware Abstraction Layer.

What is an

abstract class

What does

' abstract data type '

mean?

(not to be confused with ADT [Android Developer Tools] )

<programming> (ADT) A kind of data abstraction where a type's internal form is hidden behind a set of access functions. Values of the type are created and inspected only by calls to the access functions. This allows the implementation of the type to be changed without requiring any changes outside the module in which it is defined.

Objects and ADTs are both forms of data abstraction, but objects are not ADTs. Objects use procedural abstraction (methods), not type abstraction.

A classic example of an ADT is a stack data type for which functions might be provided to create an empty stack, to push values onto a stack and to pop values from a stack.

Reynolds paper.

Cook paper "OOP vs ADTs".

What does the term

' abstract interpretation '

mean?

<theory> A partial execution of a program which gains information about its semantics (e.g. control structure, flow of information) without performing all the calculations. Abstract interpretation is typically used by compilers to analyse programs in order to decide whether certain optimisations or transformations are applicable.

The objects manipulated by the program (typically values and functions) are represented by points in some domain. Each abstract domain point represents some set of real ("concrete") values.

For example, we may take the abstract points "+", "0" and "-" to represent positive, zero and negative numbers and then define an abstract version of the multiplication operator, *#, which operates on abstract values:

	*# | + 0 -
	---|------
	+  | + 0 -
	0  | 0 0 0
	-  | - 0 +

An interpretation is "safe" if the result of the abstract operation is a safe approximation to the abstraction of the concrete result. The meaning of "a safe approximation" depends on how we are using the results of the analysis.

If, in our example, we assume that smaller values are safer then the "safety condition" for our interpretation (#) is

	a# *# b# <= (a * b)#

where a# is the abstract version of a etc.

In general an interpretation is characterised by the domains used to represent the basic types and the abstract values it assigns to constants (where the constants of a language include primitive functions such as *). The interpretation of constructed types (such as user defined functions, sum types and product types) and expressions can be derived systematically from these basic domains and values.

A common use of abstract interpretation is strictness analysis.

See also standard interpretation.

What does the term

' abstraction '

mean?

1. Generalisation; ignoring or hiding details to capture some kind of commonality between different instances. Examples are abstract data types (the representation details are hidden), abstract syntax (the details of the concrete syntax are ignored), abstract interpretation (details are ignored to analyse specific properties).

2. <programming> Parameterisation, making something a function of something else. Examples are lambda abstractions (making a term into a function of some variable), higher-order functions (parameters are functions), bracket abstraction (making a term into a function of a variable).

What is an

' abstract machine '

?

1. <language> A processor design which is not intended to be implemented as hardware, but which is the notional executor of a particular intermediate language (abstract machine language) used in acompiler or interpreter. An abstract machine has an instruction set, a register set and a model of memory. It may provide instructions which are closer to the language being compiled than any physical computer or it may be used to make the language implementation easier to port to other platforms.

A virtual machine is an abstract machine for which an interpreter exists.

Examples: ABC, Abstract Machine Notation, ALF, CAML, F-code, FP/M, Hermes, LOWL, Christmas, SDL, S-K reduction machine, SECD, Tbl, Tcode, TL0, WAM.

2. <theory> A procedure for executing a set of instructions in some formal language, possibly also taking in input data and producing output. Such abstract machines are not intended to be constructed ashardware but are used in thought experiments about computability.

Examples: Finite State Machine, Turing Machine.

What is

Abstract Machine Notation

What is

abstract syntax

<language, data> A form of representation of data that is independent of machine-oriented structures and encodings and also of the physical representation of the data. Abstract syntax is used to give a high-level description of programs being compiled or messages passing over a communications link.

A compiler's internal representation of a program will typically be an abstract syntax tree. The abstract syntax specifies the tree's structure is specified in terms of categories such as "statement", "expression" and "identifier". This is independent of the source syntax (concrete syntax) of the language being compiled (though it will often be very similar).

A parse tree is similar to an abstract syntax tree but it will typically also contain features such as parentheses which are syntactically significant but which are implicit in the structure of the abstract syntax tree.

What is

Abstract Syntax Notation 1

<language, standard, protocol> (ASN.1, X.208, X.680) An ISO/ITU-T standard for transmitting structured data on networks, originally defined in 1984 as part of CCITT X.409 '84. ASN.1 moved to its own standard, X.208, in 1988 due to wide applicability. The substantially revised 1995 version is covered by the X.680 series.

ASN.1 defines the abstract syntax of information but does not restrict the way the information is encoded. Various ASN.1 encoding rules provide the transfer syntax (a concrete representation) of the data values whose abstract syntax is described in ASN.1. The standard ASN.1 encoding rules include BER (Basic Encoding Rules - X.209), CER (Canonical Encoding Rules), DER (Distinguished Encoding Rules) and PER (Packed Encoding Rules).

ASN.1 together with specific ASN.1 encoding rules facilitates the exchange of structured data especially between application programs over networks by describing data structures in a way that is independent of machine architecture and implementation language.

OSI Application layer protocols such as X.400 MHS electronic mail, X.500 directory services and SNMP use ASN.1 to describe the PDUs they exchange.

Documents describing the ASN.1 notations: ITU-T Rec. X.680, ISO 8824-1; ITU-T Rec. X.681, ISO 8824-2; ITU-T Rec. X.682, ISO 8824-3; ITU-T Rec. X.683, ISO 8824-4

Documents describing the ASN.1 encoding rules: ITU-T Rec. X.690, ISO 8825-1; ITU-T Rec. X.691, ISO 8825-2.

[M. Sample et al, "Implementing Efficient Encoders and Decoders for Network Data Representations", IEEE Infocom 93 Proc, v.3, pp. 1143-1153, Mar 1993. Available from Logica, UK].

See also snacc.

What is the

abstract syntax tree (AST)

What is

Abstract Type and Scheme-Definition Language (ASDL)

<language> (ASDL) A language developed as part of Esprit project GRASPIN, as a basis for generating language-based editors and environments. It combines an object-oriented type system, syntax-directed translation schemes and a target-language interface.

["ASDL - An Object-Oriented Specification Language for Syntax-Directed Environments", M.L. Christ-Neumann et al, European Software Eng Conf, Strasbourg, Sept 1987, pp.77-85].

What is the

Abstract Window(ing) Toolkit

<graphics> (AWT) Java's platform-independent windowing, graphics, and user-interface toolkit. The AWT is part of the Java Foundation Classes (JFC) - the standard API for providing a graphical user interface (GUI) for a Java program.

Compare: SWING.

["Java in a Nutshell", O'Reilly].

http://java.sun.com/products/jdk/awt/.

What is

ABSYS

<language> An early declarative language from the University of Aberdeen which anticipated a number of features of Prolog.

["ABSYS: An Incremental Compiler for Assertions", J.M. Foster et al, Mach Intell 4, Edinburgh U Press, 1969, pp. 423-429].

What is

AC2

What is

AC3

What is

ACA

Application Control Architecture

<programming> (ACA) DEC's implementation of ORB.

What is

ACAP

Application Configuration Access Protocol

<protocol> (ACAP) A protocol which enhances IMAP by allowing the user to set up address books, user options, and other data for universal access. Currently (Feb 1997) no Internet proprietary products have implemented ACAP because the Internet Engineering Task Force has not yet approved the final specification. This was expected early in 1997.

["Your E-Mail Is Obsolete", Byte, Feb 1997].

What is the

Accelerated Graphics Port (AGP)

<hardware, graphics> (AGP) A bus specification by Intel which gives low-cost 3D graphics cards faster access to main memory on personal computers than the usual PCI bus.

AGP dynamically allocates the PC's normal RAM to store the screen image and to support texture mapping, z-buffering and alpha blending.

Intel has built AGP into a chipset for its Pentium II microprocessor. AGP cards are slightly longer than a PCI card.

AGP operates at 66 MHz, doubled to 133 MHz, compared with PCI's 33 Mhz. AGP allows for efficient use of frame buffer memory, thereby helping 2D graphics performance as well.

AGP provides a coherent memory management design which allows scattered data in system memory to be read in rapid bursts. AGP reduces the overall cost of creating high-end graphics subsystems by using existing system memory.

What is an

accelerator

What is

Accent

What does the term

' accept '

mean in computer terminology

<library, networking> Berkeley Unix networking socket library routine to satisfy a connection request from a remote host. A specified socket on the local host (which must be capable of accepting the connection) is connected to the requesting socket on the remote host. The remote socket's socket address is returned.

Unix manual pages: accept(2), connect(2).

What is

Acceptable Use Policy

What is

acceptance testing

What is

Acceptance, Test or Launch Language

<language> (ATOLL) The language used for automating the checking and launch of Saturn rockets.

["SLCC ATOLL User's Manual", IBM 70-F11-0001, Huntsville AL Dec 1970].

What does the term

' acceptor '

mean in computer terminology

Finite State Machine

<mathematics, algorithm, theory> (FSM or "Finite State Automaton", "transducer") An abstract machine consisting of a set of states (including the initial state), a set of input events, a set of output events, and a state transition function. The function takes the current state and an input event and returns the new set of output events and the next state. Some states may be designated as "terminal states". The state machine can also be viewed as a function which maps an ordered sequence of input events into a corresponding sequence of (sets of) output events.

A deterministic FSM (DFA) is one where the next state is uniquely determinied by a single input event. The next state of a nondeterministic 

FSM (NFA) depends not only on the current input event, but also on an arbitrary number of subsequent input events. Until these subsequent events occur it is not possible to determine which state the machine is in.

It is possible to automatically translate any nondeterministic FSM into a deterministic one which will produce the same output given the same input. Each state in the DFA represents the set of states the NFA might be in at a given time.

In a probabilistic FSM [proper name?], there is a predetermined probability of each next state given the current state and input (compare Markov chain).

The terms "acceptor" and "transducer" are used particularly in language theory where automata are often considered as abstract machines capable of recognising a language (certain sequences of input events). An acceptor has a single Boolean output and accepts or rejects the input sequence by outputting true or false respectively, whereas a transducer translates the input into a sequence of output events.

FSMs are used in computability theory and in some practical applications such as regular expressions and digital logic design.

See also state transition diagram, Turing Machine.

[J.H. Conway, "regular algebra and finite machines", 1971, Eds Chapman & Hall].

[S.C. Kleene, "Representation of events in nerve nets and finite automata", 1956, Automata Studies. Princeton].

[Hopcroft & Ullman, 1979, "Introduction to automata theory, languages and computations", Addison-Wesley].

[M. Crochemore "tranducters and repetitions", Theoritical. Comp. Sc. 46, 1986].

What does

' Access '

mean

1. <language> An English-like query language used in the Pick operating system.

2. <database, product> Microsoft Access.

What does:

az

The Unicode Consortium develops the Unicode Standard. Their goal is to replace the existing character-sets with its standard Unicode Transformation Format (UTF).

The Unicode Standard has become a success and is implemented in XML, Java, ECMAScript (JavaScript), LDAP, CORBA 3.0, WML, etc. The Unicode standard is also supported in many operating systems and all modern browsers.

The Unicode Consortium cooperates with the leading standards development organizations, like ISO, W3C, and ECMA.

Unicode can be implemented by different character-sets. The most commonly used encodings are UTF-8 and UTF-16.

<language> /tik*l/ (Tcl) An interpreted string processing language for issuing commands to interactive programs, developed by John Ousterhout at UCB. Each application program can extend tcl with its own set of commands.

Tcl is like a text-oriented Lisp, but lets you write algebraic expressions for simplicity and to avoid scaring people away. Though originally designed to be a "scripting language" rather than for serious programming, Tcl has been used successfully for programs with hundreds of thousands of lines.

It has a peculiar but simple syntax. It may be used as an embedded interpreter in application programs. It has exceptions and packages (called libraries), name-spaces for procedures and variables, and provide/require. It supports dynamic loading of object code. It is eight-bit clean. It has only three variable types: strings, lists and associative arrays but no structures.

Tcl and its associated GUI toolkit, Tk run on all flavors of Unix, Microsoft Windows, Macintosh and VMS. Tcl runs on the Amiga and many other platforms.

Latest version: 8.0.3, as of 1998-09-25.