off-by-one error


(Or "Obi-Wan error") An exceedingly common error induced in many ways, such as by starting at zero when you should have started at one or vice-versa, or by writing "< N" instead of "<= N" or vice-versa. Often confounded with fencepost error, which is properly a particular subtype of it.

The term zeroth corrects the linguistic off-by-one error of, e.g., referring to the "1st" element of an array whose indexes start from zero.

[Jargon File]

Last updated: 1998-09-21


Microsoft Office

office automation

<application, data processing>

The use of computers or related data processing technology to do routine clerical work such as writing, filing and distributing documents. The term was used before computers in offices were the norm (1960s?).

Last updated: 2007-09-11

Office By Example


(OBE) A sequel to QBE, described in publications by Moshe Zloof of IBM in the early 1980s but apparently never implemented.

Last updated: 1998-03-14

Office Workstations Limited


(OWL) A UK software company, now a subsidiary of Matsushita (Panasonic, etc.). They previously supported the Guide hypertext system but that support is now provided by US company InfoAccess.

E-mail: <[email protected]>

[Correct address?]

Last updated: 1996-01-15

Official Production System


(OPS) The first production system (i.e. rule based) programming language, developed at CMU in 1970 and used for building expert systems. OPS was originally written in Franz Lisp and later ported to other LISP dialects.

Last updated: 2003-04-05



(Or "offline")

1. Not directly connected to the computer (e.g., an off-line tape drive), or with connection suspended ("take the printer off-line").

Contrast background, on-line.

2. Not now or not here. "Let's take this discussion off-line." Specifically used on Usenet to suggest that a discussion be moved off a public newsgroup to e-mail.

See also off-line world.

[Jargon File]

Last updated: 1996-02-02

off-line world


A die-hard nethead term for non-computer-related experience.

See also big room.

["Internet", Feb 1996].

Last updated: 1996-03-04



An index or position in an array, string, or block of memory usually a non-negative integer.

E.g. the Perl function splice(ARRAY, OFFSET, LENGTH, LIST) replaces LENGTH elements starting at index OFFSET in array with LIST, where offset zero means the start of the array.

For an Intel x86 processor with a segmented address space the offset is the position of a byte relative to the start of the segment.

Last updated: 2004-02-27



Transfer of a business process, e.g. manufacturing or customer service, from a company in one country to the same or another company in a different country. This overlaps partially with outsourcing, in which work is transferred to a different company in the same or a different country.

Last updated: 2008-12-12

off-side rule

A lexical convention due to Landin, allowing the scope of declarations in a program to be expressed by indentation. Any non-whitespace token to the left of the first such token on the previous line is taken to be the start of a new declaration. Used in, for example, Miranda and Haskell.

[P.J. Landin "The Next 700 Programming Languages", CACM vol 9 pp157-165, March 1966]

off the trolley

Describes the behaviour of a program that malfunctions and goes catatonic, but doesn't actually crash or abort. See glitch, bug, deep space.

[Jargon File]

Nearby terms:

OEMOFAoff-by-one errorOfficeoffice automationOffice By Example

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