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= I =

I didn't change anything! /interj./

An aggrieved cry often heard as bugs manifest during a regression test. The canonical reply to this assertion is "Then it works just the same as it did before, doesn't it?" See also one-line fix. This is also heard from applications programmers trying to blame an obvious applications problem on an unrelated systems software change, for example a divide-by-0 fault after terminals were added to a network. Usually, their statement is found to be false. Upon close questioning, they will admit some major restructuring of the program that shouldn't have broken anything, in their opinion, but which actually hosed the code completely.

I see no X here.

Hackers (and the interactive computer games they write) traditionally favor this slightly marked usage over other possible equivalents such as "There's no X here!" or "X is missing." or "Where's the X?". This goes back to the original PDP-10 ADVENT, which would respond in this wise if you asked it to do something involving an object not present at your location in the game.


Inferior But Marketable; It's Better Manually; Insidious Black Magic; It's Been Malfunctioning; Incontinent Bowel Movement; and a near- infinite number of even less complimentary expansions, including `International Business Machines'. See TLA. These abbreviations illustrate the considerable antipathy most hackers have long felt toward the `industry leader' (see fear and loathing).

What galls hackers about most IBM machines above the PC level isn't so much that they are underpowered and overpriced (though that does count against them), but that the designs are incredibly archaic, crufty, and elephantine ... and you can't fix them -- source code is locked up tight, and programming tools are expensive, hard to find, and bletcherous to use once you've found them. With the release of the Unix-based RIOS family this may have begun to change -- but then, we thought that when the PC-RT came out, too.

In the spirit of universal peace and brotherhood, this lexicon now includes a number of entries attributed to `IBM'; these derive from some rampantly unofficial jargon lists circulated within IBM's own beleaguered hacker underground.

IBM discount /n./

A price increase. Outside IBM, this derives from the common perception that IBM products are generally overpriced (see clone); inside, it is said to spring from a belief that large numbers of IBM employees living in an area cause prices to rise.

ICBM address /n./

(Also `missile address') The form used to register a site with the Usenet mapping project includes a blank for longitude and latitude, preferably to seconds-of-arc accuracy. This is actually used for generating geographically-correct maps of Usenet links on a plotter; however, it has become traditional to refer to this as one's `ICBM address' or `missile address', and many people include it in their sig block with that name. (A real missile address would include target altitude.)

ice /n./

[coined by Usenetter Tom Maddox, popularized by William Gibson's cyberpunk SF novels: a contrived acronym for `Intrusion Countermeasure Electronics'] Security software (in Gibson's novels, software that responds to intrusion by attempting to immobilize or even literally kill the intruder). Hence, `icebreaker': a program designed for cracking security on a system.

Neither term is in serious use yet as of early 1996, but many hackers find the metaphor attractive, and each may develop a denotation in the future. In the meantime, the speculative usage could be confused with `ICE', an acronym for "in-circuit emulator".

In ironic reference to the speculative usage, however, some hackers and computer scientists formed ICE (International Cryptographic Experiment) in 1994. ICE is a consortium to promote uniform international access to strong cryptography. ICE has a home page at http://www.tis.com/crypto/ice.html.

idempotent /adj./

[from mathematical techspeak] Acting as if used only once, even if used multiple times. This term is often used with respect to C header files, which contain common definitions and declarations to be included by several source files. If a header file is ever included twice during the same compilation (perhaps due to nested #include files), compilation errors can result unless the header file has protected itself against multiple inclusion; a header file so protected is said to be idempotent. The term can also be used to describe an initialization subroutine that is arranged to perform some critical action exactly once, even if the routine is called several times.

If you want X, you know where to find it.

There is a legend that Dennis Ritchie, inventor of C, once responded to demands for features resembling those of what at the time was a much more popular language by observing "If you want PL/I, you know where to find it." Ever since, this has been hackish standard form for fending off requests to alter a new design to mimic some older (and, by implication, inferior and baroque) one. The case X = Pascal manifests semi-regularly on Usenet's comp.lang.c newsgroup. Indeed, the case X = X has been reported in discussions of graphics software (see X).

ifdef out /if'def owt/ /v./

Syn. for condition out, specific to C.

ill-behaved /adj./

1. [numerical analysis] Said of an algorithm or computational method that tends to blow up because of accumulated roundoff error or poor convergence properties. 2. Software that bypasses the defined OS interfaces to do things (like screen, keyboard, and disk I/O) itself, often in a way that depends on the hardware of the machine it is running on or which is nonportable or incompatible with other pieces of software. In the IBM PC/MS-DOS world, there is a folk theorem (nearly true) to the effect that (owing to gross inadequacies and performance penalties in the OS interface) all interesting applications are ill-behaved. See also bare metal. Oppose well-behaved, compare PC-ism. See mess-dos.

IMHO // /abbrev./

[from SF fandom via Usenet; abbreviation for `In My Humble Opinion'] "IMHO, mixed-case C names should be avoided, as mistyping something in the wrong case can cause hard-to-detect errors -- and they look too Pascalish anyhow." Also seen in variant forms such as IMNSHO (In My Not-So-Humble Opinion) and IMAO (In My Arrogant Opinion).

Imminent Death Of The Net Predicted! /prov./

[Usenet] Since Usenet first got off the ground in 1980--81, it has grown exponentially, approximately doubling in size every year. On the other hand, most people feel the signal-to-noise ratio of Usenet has dropped steadily. These trends led, as far back as mid-1983, to predictions of the imminent collapse (or death) of the net. Ten years and numerous doublings later, enough of these gloomy prognostications have been confounded that the phrase "Imminent Death Of The Net Predicted!" has become a running joke, hauled out any time someone grumbles about the S/N ratio or the huge and steadily increasing volume, or the possible loss of a key node or link, or the potential for lawsuits when ignoramuses post copyrighted material, etc., etc., etc.

in the extreme /adj./

A preferred superlative suffix for many hackish terms. See, for example, `obscure in the extreme' under obscure, and compare highly.

inc /ink/ /v./

Verbal (and only rarely written) shorthand for increment, i.e. `increase by one'. Especially used by assembly programmers, as many assembly languages have an inc mnemonic. Antonym: dec.

incantation /n./

Any particularly arbitrary or obscure command that one must mutter at a system to attain a desired result. Not used of passwords or other explicit security features. Especially used of tricks that are so poorly documented that they must be learned from a wizard. "This compiler normally locates initialized data in the data segment, but if you mutter the right incantation they will be forced into text space."

include /vt./

[Usenet] 1. To duplicate a portion (or whole) of another's message (typically with attribution to the source) in a reply or followup, for clarifying the context of one's response. See the discussion of inclusion styles under "Hacker Writing Style". 2. [from C] #include <disclaimer.h> has appeared in sig blocks to refer to a notional `standard disclaimer file'.

include war /n./

Excessive multi-leveled inclusion within a discussion thread, a practice that tends to annoy readers. In a forum with high-traffic newsgroups, such as Usenet, this can lead to flames and the urge to start a kill file.

indent style /n./

[C programmers] The rules one uses to indent code in a readable fashion. There are four major C indent styles, described below; all have the aim of making it easier for the reader to visually track the scope of control constructs. The significant variable is the placement of `{' and `}' with respect to the statement(s) they enclose and to the guard or controlling statement (if, else, for, while, or do) on the block, if any.

`K&R style' -- Named after Kernighan & Ritchie, because the examples in K&R are formatted this way. Also called `kernel style' because the Unix kernel is written in it, and the `One True Brace Style' (abbrev. 1TBS) by its partisans. The basic indent shown here is eight spaces (or one tab) per level; four spaces are occasionally seen, but are much less common.

if (<cond>) {

`Allman style' -- Named for Eric Allman, a Berkeley hacker who wrote a lot of the BSD utilities in it (it is sometimes called `BSD style'). Resembles normal indent style in Pascal and Algol. Basic indent per level shown here is eight spaces, but four spaces are just as common (esp. in C++ code).

if (<cond>)

`Whitesmiths style' -- popularized by the examples that came with Whitesmiths C, an early commercial C compiler. Basic indent per level shown here is eight spaces, but four spaces are occasionally seen.

if (<cond>)

`GNU style' -- Used throughout GNU EMACS and the Free Software Foundation code, and just about nowhere else. Indents are always four spaces per level, with { and } halfway between the outer and inner indent levels.

if (<cond>)

Surveys have shown the Allman and Whitesmiths styles to be the most common, with about equal mind shares. K&R/1TBS used to be nearly universal, but is now much less common (the opening brace tends to get lost against the right paren of the guard part in an if or while, which is a Bad Thing). Defenders of 1TBS argue that any putative gain in readability is less important than their style's relative economy with vertical space, which enables one to see more code on one's screen at once. Doubtless these issues will continue to be the subject of holy wars.

index /n./

See coefficient of X.

infant mortality /n./

It is common lore among hackers (and in the electronics industry at large; this term is possibly techspeak by now) that the chances of sudden hardware failure drop off exponentially with a machine's time since first use (that is, until the relatively distant time at which enough mechanical wear in I/O devices and thermal-cycling stress in components has accumulated for the machine to start going senile). Up to half of all chip and wire failures happen within a new system's first few weeks; such failures are often referred to as `infant mortality' problems (or, occasionally, as `sudden infant death syndrome'). See bathtub curve, burn-in period.

infinite /adj./

Consisting of a large number of objects; extreme. Used very loosely as in: "This program produces infinite garbage." "He is an infinite loser." The word most likely to follow `infinite', though, is hair. (It has been pointed out that fractals are an excellent example of infinite hair.) These uses are abuses of the word's mathematical meaning. The term `semi-infinite', denoting an immoderately large amount of some resource, is also heard. "This compiler is taking a semi-infinite amount of time to optimize my program." See also semi.

infinite loop /n./

One that never terminates (that is, the machine spins or buzzes forever and goes catatonic). There is a standard joke that has been made about each generation's exemplar of the ultra-fast machine: "The Cray-3 is so fast it can execute an infinite loop in under 2 seconds!"

Infinite-Monkey Theorem /n./

"If you put an infinite number of monkeys at typewriters, eventually one will bash out the script for Hamlet." (One may also hypothesize a small number of monkeys and a very long period of time.) This theorem asserts nothing about the intelligence of the one random monkey that eventually comes up with the script (and note that the mob will also type out all the possible incorrect versions of Hamlet). It may be referred to semi-seriously when justifying a brute force method; the implication is that, with enough resources thrown at it, any technical challenge becomes a one-banana problem.

This theorem was first popularized by the astronomer Sir Arthur Eddington. It became part of the idiom of techies via the classic SF short story "Inflexible Logic" by Russell Maloney, and many younger hackers know it through a reference in Douglas Adams's "Hitchhiker's Guide to the Galaxy".

infinity /n./

1. The largest value that can be represented in a particular type of variable (register, memory location, data type, whatever). 2. `minus infinity': The smallest such value, not necessarily or even usually the simple negation of plus infinity. In @Math{N}-bit twos-complement arithmetic, infinity is @Math{2^(N-1) - 1} but minus infinity is @Math{- (2^(N-1))}, not @Math{-(2^(N-1) - 1)}. Note also that this is different from time T equals minus infinity, which is closer to a mathematician's usage of infinity.

inflate /vt./

To decompress or puff a file. Rare among Internet hackers, used primarily by MS-DOS/Windows types.

Infocom /n./

A now-legendary games company, active from 1979 to 1989, that commercialized the MDL parser technology used for Zork to produce a line of text adventure games that remain favorites among hackers. Infocom's games were intelligent, funny, witty, erudite, irreverent, challenging, satirical, and most thoroughly hackish in spirit. The physical game packages from Infocom are now prized collector's items. The software, thankfully, is still extant; Infocom games were written in a kind of P-code and distributed with a P-code interpreter core, and freeware emulators for that interpreter have been written to permit the P-code to be run on platforms the games never originally graced.

(Emulators that can run Infocom game ZIPs are vailable at //wuarchive.wustl.edu:/doc/misc/if-archive/infocom.)

initgame /in-it'gaym/ /n./

[IRC] An IRC version of the venerable trivia game "20 questions", in which one user changes his nick to the initials of a famous person or other named entity, and the others on the channel ask yes or no questions, with the one to guess the person getting to be "it" next. As a courtesy, the one picking the initials starts by providing a 4-letter hint of the form sex, nationality, life-status, reality-status. For example, MAAR means "Male, American, Alive, Real" (as opposed to "fictional"). Initgame can be surprisingly addictive. See also hing.

[1996 update: a recognizable version of the initgame has become a staple of some radio talk shows in the U.S. We had it first! -- ESR]

insanely great /adj./

[Mac community, from Steve Jobs; also BSD Unix people via Bill Joy] Something so incredibly elegant that it is imaginable only to someone possessing the most puissant of hacker-natures.

INTERCAL /in't*r-kal/ /n./

[said by the authors to stand for `Compiler Language With No Pronounceable Acronym'] A computer language designed by Don Woods and James Lyons in 1972. INTERCAL is purposely different from all other computer languages in all ways but one; it is purely a written language, being totally unspeakable. An excerpt from the INTERCAL Reference Manual will make the style of the language clear:

It is a well-known and oft-demonstrated fact that a person whose work is incomprehensible is held in high esteem. For example, if one were to state that the simplest way to store a value of 65536 in a 32-bit INTERCAL variable is:

DO :1 <- #0$#256

any sensible programmer would say that that was absurd. Since this is indeed the simplest method, the programmer would be made to look foolish in front of his boss, who would of course have happened to turn up, as bosses are wont to do. The effect would be no less devastating for the programmer having been correct.

INTERCAL has many other peculiar features designed to make it even more unspeakable. The Woods-Lyons implementation was actually used by many (well, at least several) people at Princeton. The language has been recently reimplemented as C-INTERCAL and is consequently enjoying an unprecedented level of unpopularity; there is even an alt.lang.intercal newsgroup devoted to the study and ... appreciation of the language on Usenet.

An INTERCAL implementation is available at the Retrocomputing Museum, http://www.ccil.org/retro.

interesting /adj./

In hacker parlance, this word has strong connotations of `annoying', or `difficult', or both. Hackers relish a challenge, and enjoy wringing all the irony possible out of the ancient Chinese curse "May you live in interesting times". Oppose trivial, uninteresting.

Internet /n./

The mother of all networks. First incarnated beginning in 1969 as the ARPANET, a U.S. Department of Defense research testbed. Though it has been widely believed that the goal was to develop a network architecture for military command-and-control that could survive disruptions up to and including nuclear war, this is a myth; in fact, ARPANET was conceived from the start as a way to get most economical use out of then-scarce large-computer resources.

As originally imagined, ARPANET's major use would have been to support what is now called remote login and more sophisticated forms of distributed computing, but the infant technology of electronic mail quickly grew to dominate actual usage. Universities, research labs and defense contractors early discovered the Internet's potential as a medium of communication between humans and linked up in steadily increasing numbers, connecting together a quirky mix of academics, techies, hippies, SF fans, hackers, and anarchists. The roots of this lexicon lie in those early years.

Over the next quarter-century the Internet evolved in many ways. The typical machine/OS combination moved from DEC PDP-10s and PDP-20s, running TOPS-10 and TOPS-20, to PDP-11s and VAXes and Suns running Unix, and in the 1990s to Unix on Intel microcomputers. The Internet's protocols grew more capable, most notably in the move from NCP/IP to TCP/IP in 1982 and the implementation of Domain Name Service in 1983. With TCP/IP and DNS in place. It was around this time that people began referring to the collection of interconnected networks with ARPANET at its core as "the Internet".

The ARPANET had a fairly strict set of participation guidelines -- connected institutions had to be involved with a DOD-related research project. By the mid-80s, many of the organizations clamoring to join didn't fit this profile. In 1986, the National Science Foundation built NSFnet to open up access to its five regional supercomputing centers; NSFnet became the backbone of the Internet, replacing the original ARPANET pipes (which were formally shut down in 1990). Between 1990 and late 1994 the pieces of NSFnet were sold to major telecommunications companies until the Internet backbone had gone completely commercial.

That year, 1994, was also the year the mainstream culture discovered the Internet. Once again, the killer app was not the anticipated one -- rather, what caught the public imagination was the hypertext and multimedia features of the World Wide Web. As of early 1996, the Internet has seen off its only serious challenger (the OSI protocol stack favored by European telecom monopolies) and is in the process of absorbing into itself many of of the proprietary networks built during the second wave of wide-area networking after 1980. It is now a commonplace even in mainstream media to predict that a globally-extended Internet will become the key unifying communications technology of the next century. See also network, the and Internet address.

Internet address /n./

1. [techspeak] An absolute network address of the form foo@bar.baz, where foo is a user name, bar is a sitename, and baz is a `domain' name, possibly including periods itself. Contrast with bang path; see also network, the and network address. All Internet machines and most UUCP sites can now resolve these addresses, thanks to a large amount of behind-the-scenes magic and PD software written since 1980 or so. See also bang path, domainist. 2. More loosely, any network address reachable through Internet; this includes bang path addresses and some internal corporate and government networks.

Reading Internet addresses is something of an art. Here are the four most important top-level functional Internet domains followed by a selection of geographical domains:

commercial organizations
educational institutions
U.S. government civilian sites
U.S. military sites

Note that most of the sites in the com and edu domains are in the U.S. or Canada.

sites in the U.S. outside the functional domains
sites in the ex-Soviet Union (see kremvax).
sites in the United Kingdom

Within the us domain, there are subdomains for the fifty states, each generally with a name identical to the state's postal abbreviation. Within the uk domain, there is an ac subdomain for academic sites and a co domain for commercial ones. Other top-level domains may be divided up in similar ways.


1. [techspeak] /n./ On a computer, an event that interrupts normal processing and temporarily diverts flow-of-control through an "interrupt handler" routine. See also trap. 2. /interj./ A request for attention from a hacker. Often explicitly spoken. "Interrupt -- have you seen Joe recently?" See priority interrupt. 3. Under MS-DOS, nearly synonymous with `system call', because the OS and BIOS routines are both called using the INT instruction (see interrupt list, the) and because programmers so often have to bypass the OS (going directly to a BIOS interrupt) to get reasonable performance.

interrupt list, the /n./

[MS-DOS] The list of all known software interrupt calls (both documented and undocumented) for IBM PCs and compatibles, maintained and made available for free redistribution by Ralf Brown <ralf@cs.cmu.edu>. As of late 1992, it had grown to approximately two megabytes in length.

interrupts locked out /adj./

When someone is ignoring you. In a restaurant, after several fruitless attempts to get the waitress's attention, a hacker might well observe "She must have interrupts locked out". The synonym `interrupts disabled' is also common. Variations abound; "to have one's interrupt mask bit set" and "interrupts masked out" are also heard. See also spl.

IRC /I-R-C/ /n./

[Internet Relay Chat] A worldwide "party line" network that allows one to converse with others in real time. IRC is structured as a network of Internet servers, each of which accepts connections from client programs, one per user. The IRC community and the Usenet and MUD communities overlap to some extent, including both hackers and regular folks who have discovered the wonders of computer networks. Some Usenet jargon has been adopted on IRC, as have some conventions such as emoticons. There is also a vigorous native jargon, represented in this lexicon by entries marked `[IRC]'. See also talk mode.

iron /n./

Hardware, especially older and larger hardware of mainframe class with big metal cabinets housing relatively low-density electronics (but the term is also used of modern supercomputers). Often in the phrase big iron. Oppose silicon. See also dinosaur.

Iron Age /n./

In the history of computing, 1961--1971 -- the formative era of commercial mainframe technology, when ferrite-core dinosaurs ruled the earth. The Iron Age began, ironically enough, with the delivery of the first minicomputer (the PDP-1) and ended with the introduction of the first commercial microprocessor (the Intel 4004) in 1971. See also Stone Age; compare elder days.

iron box /n./

[Unix/Internet] A special environment set up to trap a cracker logging in over remote connections long enough to be traced. May include a modified shell restricting the cracker's movements in unobvious ways, and `bait' files designed to keep him interested and logged on. See also back door, firewall machine, Venus flytrap, and Clifford Stoll's account in " The Cuckoo's Egg" of how he made and used one (see the Bibliography in Appendix C). Compare padded cell.

ironmonger /n./

[IBM] A hardware specialist (derogatory). Compare sandbender, polygon pusher.


Common abbreviation for Internet Service Provider, a kind of company that barely existed before 1993. ISPs sell Internet access to the mass market. While the big nationwide commercial BBSs with Internet access (like America Online, CompuServe, GEnie, Netcom, etc.) are technically ISPs, the term is usually reserved for local or regional small providers (often run by hackers turned entrepreneurs) who resell Internet access cheaply without themselves being information providers or selling advertising. Compare NSP.

ITS /I-T-S/ /n./

1. Incompatible Time-sharing System, an influential though highly idiosyncratic operating system written for PDP-6s and PDP-10s at MIT and long used at the MIT AI Lab. Much AI-hacker jargon derives from ITS folklore, and to have been `an ITS hacker' qualifies one instantly as an old-timer of the most venerable sort. ITS pioneered many important innovations, including transparent file sharing between machines and terminal-independent I/O. After about 1982, most actual work was shifted to newer machines, with the remaining ITS boxes run essentially as a hobby and service to the hacker community. The shutdown of the lab's last ITS machine in May 1990 marked the end of an era and sent old-time hackers into mourning nationwide (see high moby). The Royal Institute of Technology in Sweden is maintaining one `live' ITS site at its computer museum (right next to the only TOPS-10 system still on the Internet), so ITS is still alleged to hold the record for OS in longest continuous use (however, WAITS is a credible rival for this palm). 2. A mythical image of operating-system perfection worshiped by a bizarre, fervent retro-cult of old-time hackers and ex-users (see troglodyte, sense 2). ITS worshipers manage somehow to continue believing that an OS maintained by assembly-language hand-hacking that supported only monocase 6-character filenames in one directory per account remains superior to today's state of commercial art (their venom against Unix is particularly intense). See also holy wars, Weenix.


Abbreviation for `It Would Be Nice If'. Compare WIBNI.


[Usenet] Abbreviation for `Insert Your Favorite Ethnic Group'. Used as a meta-name when telling ethnic jokes on the net to avoid offending anyone. See JEDR.

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