Adapter Card Definition, What is Adapter Card

An adapter card is an internal card that enables your computer to communicate with another peripheral such as a monitor. This is term also can be referred to a networking interface card that is populated into a product like a Cisco 6509 chassis.

Accent Mark Definition, What are Accent Marks

A diacritical mark or diacritic, sometimes called an accent mark, is a mark added to a letter to alter a word's pronunciation (i.e., vowel marks) or to distinguish between similar words. The word derives from the Greek word διακριτικός (diakritikos, distinguishing). Note that diacritic is a noun and diacritical is the corresponding adjective.

A accent mark can appear above or below the letter to which it is added, or in some other position; however, note that not all such marks are diacritical. For example, in English, the tittle (dot) on the letters i and j is not a accent mark, but rather part of the letter itself. Further, a mark may be diacritical in one language, but not in another; for example, in Catalan, Portuguese and Spanish, u and ü are considered the same letter, while in German, Estonian, Hungarian, Turkish and Azeri they are considered to be separate letters.

The main usage of a diacritic is to change the phonetic meaning of the letter, but the term is also used in a more general sense of changing the meaning of the letter or even the whole word. Examples are writing numerals in numeral systems, such as early Greek numerals and marking abbreviations with the titlo in old Slavic texts.

Types of Diacritic

• ( ˙ ) anunaasika superdot
• ( . ) anusvaara subdot, used in Sanskrit and in Old Irish spelling
• ( ¸ ) cedilla or "cédille" in French, Latvian, Portuguese and other languages.
• ( ˛ ) ogonek or "Polish hook"
• ( ° ) kroužek or ring; unlike in Czech, in the Scandinavian languages this is not considered a diacritic but an integral part of the character å, a separate letter in Swedish, Norwegian and Danish.
• ( ˘ ) breve (literally "short"); part of the character when used in Esperanto; also used in Romanian and Ko
• ( ˇ ) caron or háček ("little hook" in Czech). In Slovak it is called mäkčeň ("softener" or "palatalization mark"), in Slovenian strešica ("little roof"), in Croatian and Serbian kvačica ("little hook").
• ( ^ ) circumflex, part of the character when used in Esperanto, also in Slovak is used on "o" and it is called vokáň
• ( ¯ ) macron, also known as a "long mark" in English and Latvian; used to mark long vowels in Māori, Hawaiian, Japanese Rōmaji, Sanskrit transliteration and elsewhere.
• ( ¨ ) diaeresis (also dieresis) or umlaut, a diacritic in some languages, but part of the character in the German, Swedish, Finnish, Ukrainian and Russian languages. Also used in French, Portuguese, Spanish, Swiss German, Dutch, Greek and Turkish.
• ( ` ) grave accent
• ( ´ ) acute accent
• ( ˝ ) double acute accent
• (  ̔ ) spiritus asper or rough breathing mark
• (  ̓ ) spiritus lenis or smooth (or soft) breathing mark
• hook (dấu hỏi), as used in Vietnamese

Marks that are sometimes diacritics, but also have other uses, are:

• ( | ) bar through the basic letter
• ( , ) comma
• ( ~ ) tilde
• (  ҃ ) titlo, used to indicate abbreviation in the early Cyrillic alphabet
• ( ' ) apostrophe
• ( : ) colon, used to attach native affixes (such as case markers) to foreign words and abbreviations
• ( - ) hyphen - in English, hyphens can be used to break words between syllables, to resolve ambiguities in pronunciation:
• repair (fix) compared to re-pair (pair again).
• Kuringgai becomes Ku-ring-gai.

Diacritic Usage

Catalan has grave, acute, cedilla and diaeresis.

Several Chinese romanizations use umlaut, but only on u (ü). In Hanyu Pinyin, the five tones of Mandarin Chinese are denoted by the macron (First tone), acute (second tone), caron (third tone) and grave (Fourth tone) diacritics. example:ā,á,ǎ,à.

Czech has acute, caron and ring.

Dutch uses diaeresis. For example in ruïne it means that the u and i are separately pronounced in their usual way, and not in the way that the combination ui is normally pronounced. Thus it works as a separation sign and not as an indication for an alternative version of the i. Diacritics can be used for emphasis (érg koud for very cold) or for disambiguation between a number of words that are spelled the same when context doesn't indicate the correct meaning (één appel = one apple, een appel = an apple; vóórkomen = to occur, voorkómen = to prevent). Grave and acute accents are used on a very small number of words, mostly loanwords.

English is one of the few European languages that does not use diacritical marks (along with Basque), except for some borrowings taken unchanged mainly from French, in which case the diacritic is often omitted. The most likely words to keep the diacritic are apparently those containing é (such as café) and the word naïve (See List of English words with diacritics). English used to use the diaeresis much like Dutch does still (as in words such as "coöperate"), but this has been falling out of use (The New Yorker's house style being one of the few publications to retain this feature). The grave accent was also once used cheifly in poetry and songs to modify the pronunciation of words ending in -ed; -èd indicates a separate syllable.

In Estonian, the umlaut is used much as in Finnish, but also with ü instead of Finnish y. Another vowel õ also occurs in Estonian. Carons in š or ž may appear only in foreign proper names and loanwords, but may be also substituted with sh or zh in some texts. Apostrophe can be used in declension of some foreign names to separate the stem from any declension endings; e.g., Monet' or Monet'sse for the genitive case and illative case, respectively, for (the famous painter) "Monet".

French uses grave, acute, circumflex, cedilla and diaeresis. However, not all diacritics occur on all vowels in French:

• Acute (accent aigu) only occurs on e (é, pronounced /e/)
• Grave (accent grave) occurs on e (è, pronounced /ε/), a (à), and u (ù)
• Circumflex (accent circonflexe) occurs on all vowels: e (ê, pronounced /ε/), a (â, pronounced /α/), i (î), o (ô, pronounced /o/), and u (û; if occurring in the combination eû, pronounced /ø/)
• Cedilla (cédille) is used only under the c (ç, pronounced /s/). It is used in cases in which a c is soft before a, o, or u, such as ça (pronounced /sa/, not /ka/).
• Diaeresis (tréma) occurs on e (ë), i (ï), u (ü), and y (ÿ). The diaeresis only occurs on y in a few proper nouns, including Louÿs and L'Haÿ-les-Roses. The mark's function is to indicate that the vowel is pronounced separately from the one just before it.
• Diacritics are sometimes omitted from capitalized letters, especially in France. The origin of this omission lies in mechanical typesetting in which the addition of a diacritic to a capital letter would change its height and thus require separate versions of a capital letter with and without its diacritc: this was deemed impractical and the diacritics were thus dropped from capital letters. However, with the advent of digital typography the use of diacritics on capital letters has become more prevalent, especially on documents created in a word processor (as opposed to professional work designed for widespread consumption).
• Not all French diacritics affect pronunciation. However, all cases in which they do have been noted in the foregoing.

Finnish uses a colon to decline loanwords and abbreviations; e.g., USA:han for the illative case of "USA". Also characters ä and ö are part of the Finnish alphabet (a and o with Umlaut).

German and Swiss German have the Umlaut (¨). This can be used over a, o, or u to indicate vowel modification. For instance: Ofen (/'o:fən/); Öfen (/'ø:fən/), which in this case makes the difference between singular and plural (“oven”/“ovens”). The sign originated in a superscript e; a handwritten Sütterlin e resembles two parallel vertical lines, like an umlaut.

Hawaiian has kahakos (macrons) and okinas (ʻ); often rendered as (‘).

Hebrew has many various diacritic marks known as Niqqud that are used above and below script to represent vowels. These Niqqud must be distinguished from Cantillation, which are keys to pronunciation and syntax.

The International Phonetic Alphabet uses diacritic symbols and diacritic letters to indicate phonetic features or secondary articulations.

Irish uses acute accent to indicate that the vowel is long. It is known as síneadh fada (long sign) or simply fada (long) in Irish.

Italian mainly has the acute and the grave (à, è/é, ì, ò/ó, ù).

• They indicate the stressed vowel of a word, chiefly on the final vowel of words of more than one syllable (thus verità, "truth", Gesù, "Jesus", finì, "[he/she/it] ended"). These two accents are furthermore used to avoid mispronunciations in monosyllables containing rising diphthongs (as in più, "more", which would otherwise be stressed on the i; also e.g. in ciò, "that, it", where the -i- is mute, [tʃɔ], but that would be read *[tʃio] without the accent), and to distinguish words that would otherwise be homographs (such as te, "you", and tè, "tea", or se, "if", and sé, "himself/herself/themselves"). The standard rule in contemporary Italian is the following: on a, i and u only the grave is used (thus à, ì, ù, as in the three examples given before); on the vowels e and o, that both represent two different vowel-sounds, the acute indicates the close pronunciation (é = /e/, ó = /o/), the grave the open one (è = /ε/, ò = /ɔ/): examples are perché, "because, why", and cioè, "namely, that is"; parlò, "[he/she] spoke", and cómpito, "task" (in the last case the accent is optional, but may be used to distinguish the word from compìto, "accomplished, polite").

• Italian may also use the circumflex (^) on the vowel i: this -î is optionally (but rarely) used to indicate the contraction of an original double i at the end of some words (properly of latinisms only), usually in plural form (e.g. assassini may mean both "murderers", plural of assassino, and "murders", plural of assassinio, so assassinii or assassinî is sometimes used in the sense of "murders"; in several cases the distinction is better expressed using stress marks: thus prìncipi means "princes", princìpi means "principles, beginnings"; conservatóri means "conservatives", conservatòri "academies of music, conservatoires"). In older texts a final -j (principj, etc.) was sometimes used. But the usual form is -i (one i only), and the cases of possible ambiguities are actually very rare.

Romanized Japanese (Romaji) uses diacritics to mark long vowels. The Hepburn romanization system uses a macron to mark long vowels, and the Kunrei-shiki and Nihon-shiki systems use a circumflex.

Lithuanian uses the acute, grave and tilde in dictionaries to indicate stress types in the language's pitch stress system. In general usage, where letters appear with the caron (č, š and ž) they are considered as separate letters from c, s or z and collated separately; letters with the ogonek (ą, ę, į and ų), the macron (ū) and the superdot (ė) are considered as separate letters as well, but not given a unique collation order.

Portuguese uses the acute accent, the circumflex accent, the grave accent, the tilde, and the cedilla, to denote vowel stress, vowel height, nasalization, and other sound changes. Brazilian Portuguese also uses the diaeresis mark. Accented letters are not considered separate characters.

Many Slavic and Baltic languages use caron to signify either palatalisation or iotation.

Many Slavic languages that use the Latin alphabet have ogonek and bar.

Slovak has acute, caron, circumflex (only above o) and diaresis (only above a).

Spanish uses acute, diaeresis and tilde. Acute is used on a vowel in a stressed syllable in words with irregular stress patterns. It can also be used to "break" a diphthong as in tío (pronounced /'tio/, and not /tjo/ as it would be without the accent). Moreover, the acute can be used to distinguish words that otherwise are spelt alike, such as si ( = "if") and sí ( = "yes"), and also to distinguish interrogative and relative words otherwise spelt alike, such as donde/¿dónde? ( = "where") or como/¿cómo? ( = "as"/"how?"). Tilde is used on n, forming a separate letter (ñ) in the Spanish alphabet. Diaeresis is used only over u (ü) so that it is pronounced /w/ in the combinations gue and gui (where u is normally silent), for example ambigüedad. In poetry, diaeresis may be used on i and u as a way to force hiatus.

Swedish sometimes uses the acute accent, exclusively over the letter e to show non-standard stress, like in kafé or resumé. Usage isn't mandatory, though.

Tagalog uses a hyphen after a consonant to indicate a syllable break (nag-alis /nag·a·lís/ as opposed to nagalis /na·ga·lís/). A hyphen is not necessary between two vowels, vowels being distinctly pronounced in Tagalog (tauhan /ta·ú·han/, buo /bu·ô/).

Tamil does not have any diacritics in itself, but uses the Western numerals 2, 3 and 4 as diacritics to represent aspirated, voiced, and voiced-aspirated consonants when the Tamil script is used to write to long passages in Sanskrit.

Thai has its own system of diacritics derived from Indic numerals.

Vietnamese uses acute (dấu sắc), grave (dấu huyền), tilde (dấu ngã), dot below (dấu nặng) and hook (dấu hỏi) on vowels as tone indicators.

Welsh uses the circumflex, diaeresis, acute and grave accents on its seven vowels a, e, i, o, u, w, y. The most common is the circumflex (which it calls to bach, meaning "little roof") to denote a long vowel, usually to disambiguate it from a similar word with a short vowel. The rarer grave accent has the opposite effect, shortening vowel sounds which would usually be pronounced long. The acute accent and diaeresis are also occasionally used, to denote stress and vowel separation respectively. The w-circumflex and y-circumflex are among the most common accented characters in Welsh, but unusual in languages generally, and were until recently very hard to obtain in word-processed and HTML documents.

Non-Diacritic Usage

Esperanto has a separate letter which is a u with a breve over it, and letters which are c, g, h, j and s with the circumflex over them. These are not diacritic marks, but necessary parts of entirely separate letters.

Estonian has a distinct letter õ which contains a non-diacritical tilde. Estonian "dotted vowels" ä, ö, ü are similar to German, but these are also distinct letters, not containing umlauts. All four of these letters have their own place in the alphabet (between w and x).

Faroese and Icelandic use acute accents, digraphs, and other special letters. All are considered separate letters, and have their own place in the alphabet:

• Faroese: á, ð, í, ó, ú, ý, æ and ø
• Icelandic: á, ð, é, í, ó, ú, ý, æ, ö and þ

Finnish uses dotted vowels (ä and ö) similar to in Swedish, and å, š and ž in foreign names and loanwords; they are considered distinct letters and collate after z.

Hungarian uses the acute and double acute accent (unique to Hungarian): áéíóú and őű. The diacritic marks over the letters ö and ü are not umlauts. The acute accent indicates the long form of a vowel, while the double acute performs the same function for ö and ü. Both long and short forms of the vowels are listed separately in the Hungarian alphabet.

Maltese uses a C, G, and Z with a dot over them (Ċ, Ġ, Ż), and also has a H with an extra horizontal bar. For upper case H, the extra bar is written slightly above the usual bar. For lower case H, the extra bar is written crossing the vertical, like a t, and not touching the lower part (Ħ, ħ). The above letters are considered separate letters, not dicritics. Maltese sometimes uses diacritics on some vowels to indicate stress or long vowels, however this usage is restricted to pronunciation assistance in dictionaries. The letter 'c' without a dot has fallen out of use due to redundancy. 'ċ' is pronounced like the English 'ch' and 'k' is used as a hard c as in 'cat'. The Maltese Z is pronounced like a 'ts' (Zokkor (sugar) is pronounced 'tsoh-kor') while 'ż' is closer to the English 'z' as in 'żarbun (shoe), pronounced 'zahr-boon'. 'G' is a hard 'g' sound, pronounced like the 'g' in the English word 'sugar' while 'ġ' is a soft 'g' as in 'ġobon' (cheese), pronounced 'job-ohn'.

Romanian uses a breve on the letter a (ă) to indicate the sound schwa (/ə/), as well as a circumflex over the letters a (â) and i (î) for the sound /ɨ/. Romanian also writes a comma below the letters s (ș) and t (ț) to represent the sounds /ʃ/ and /ʦ/, respectively.

Among the Scandinavian languages, Danish and Norwegian have long used ash (æ, actually a ligature) and o-slash (ø), but have more recently incorporated a-ring (å) after Swedish example. Historically the å has developed from a ligature by writing a small a on top of the letter a; if an å character is unavailable, some Scandinavian languages allow the substitution of a doubled a. The Scandinavian languages collate these letters after z, but have different collation standards. In Swedish, the order å, ä, ö is used, while Danish and Norwegian follow the order æ, ø, å instead.

Swedish uses characters identical to a-diaeresis (ä) and o-diaeresis (ö) in the place of ash and o-slash in addition to the a-circle (å). Historically the diaresis for the Swedish letters ä and ö, like the German umlaut, has developed from a small gothic e written on top of the letters.

Turkish uses a G with a breve (Ğ), two letters with a diaeresis (Ö and Ü, representing two rounded front vowels), two letters with a cedilla (Ç and Ş, representing the affricates /tʃ/ and /ʃ/), and also possesses a dotted capital İ (and a dotless lowercase ı representing a high unrounded back vowel). In Turkish each of these are separate letters, rather than versions of other letters, where dotted capital İ and lower case i are the same letter, as are dotless capital I and lowercase ı. Typographically, Ç and Ş are often rendered with a subdot, as in Ṣ; when a hook is used, it tends to have more a comma shape than the usual cedilla. See also Turkish alphabet.

Vietnamese uses the horn for the letters ơ and ư; circumflex for the letters â, ê, and ô; breve for the letter ă; and a bar through the letter đ. See Vietnamese alphabet for their collation order.

In all these cases they are not seen as additional marks over the vowel, but are actually a necessary part of these characters, as they represent entirely different sounds to the basic forms.

Cyrillic alphabets

Belarusian has a letter ў.

Russian has the letter ё, usually replaced in print by е, although it has a different pronunciation. Ё is still used in children's books and in handwriting. A minimal pair is все (vse, "all" pl.) and всё (vsio, "everything" n. sg.).

Bulgarian, Russian and Ukrainian have the letter й.

Ukrainian also has the letter ï.

Acute accents are also used in Slavic language dictionaries and textbooks to indicate lexical stress, placed over the vowel of the stressed syllable. This can also serve to disambiguate meaning (e.g., in Russian писа́ть (pisát) means "to write", but пи́сать (písat) means "to piss").

Non-Alphabetic Scripts

Some non-alphabetic scripts also employ symbols that function essentially as diacritics.


Non-pure abjads (such as Hebrew and Arabic script) and abugidas use diacritics for denoting vowels. Hebrew and Arabic also indicate consonant doubling and change with diacritics; Hebrew and Devanagari use them for foreign sounds. Devanagari and related abugidas also use a diacritical mark called a virama to mark the absence of a vowel.

The Japanese hiragana and katakana syllabaries use the dakuten (゛) and handakuten (゜) symbols, also known as ten-ten and maru, to indicate voiced consonants.


Alphabetization or Collation

Modern computer technology was developed mostly in the English speaking countries, so data formats, keyboard layouts, etc. were developed with an English bias; a "simple" alphabet without diacritical marks. This has led to fears internationally that the marks and accents may become obsolete to facilitate the worldwide exchange of data. Efforts have been made to create domain names that extend further than the English alphabet: the internationalized domain names, example: "pokémon.com".

Depending on the keyboard layout, which differs amongst countries, it is more or less easy to enter letters with diacritics on computers and typewriters. Some have their own keys, some are created by first pressing the key with the diacritic mark followed by the letter to place it on. Such a key is sometimes referred to as a dead key, as it produces no output of its own, but modifies the output of the key pressed after it.

In modern Microsoft Windows operating systems, the keyboard layout US International allows one to type almost all diacritics directly: "+e gives ë, ~+o gives õ, etc. On Apple Macintosh computers, there are keyboard shortcuts for the most common diacritics; Option-e followed by a vowel places an acute accent, Option-u folowed by a vowel gives an umlat, option-c gives a cedelle, etc. Diacritics can be composed in most X Window System keyboard layouts.

On computers it is also a matter of available code pages, whether you can use certain diacritics. Unicode solves this problem by assigning every known character its own code; if this code is known most modern computer systems provide a method to input it. With Unicode it is also possible to combine diacritical marks with most characters.

Accuracy Definition, What is Accuracy

In general, refers to precision and/or exactness, but to dig into this term...

In the fields of science, engineering, industry and statistics, accuracy is the degree of conformity of a measured or calculated quantity to its actual (true) value. Accuracy is closely related to precision, also called reproducibility or repeat-ability  the degree to which further measurements or calculations will show the same or similar results.

The results of calculations or a measurement can be accurate but not precise; precise but not accurate; neither; or both. A result is called valid if it is both accurate and precise.

The related terms in surveying are error (random variability in research) and bias (non-random or directed effects caused by a factor or factors unrelated by the independent variable).


Accuracy vs Precision - The Target Analogy

Accuracy is the degree of veracity while precision is the degree of reproducibility. The analogy used here to explain the difference between accuracy and precision is the target comparison.

In this analogy, repeated measurements are compared to arrows that are fired at a target. Accuracy describes the closeness of arrows to the bulls-eye at the target center. Arrows that strike closer to the bulls-eye are considered more accurate. The closer a system's measurements to the accepted value, the more accurate the system is considered to be.

To continue the analogy, if a large number of arrows are fired, precision would be the size of the arrow cluster. (When only one arrow is fired, precision is the size of the cluster one would expect if this were repeated many times under the same conditions.) When all arrows are grouped tightly together, the cluster is considered precise since they all struck close to the same spot, if not necessarily near the bullseye. The measurements are precise, though not necessarily accurate.

However, it is not possible to reliably achieve accuracy in individual measurements without precision — if the arrows are not grouped close to one another, they cannot all be close to the bulls-eye  (Their average position might be an accurate estimation of the bulls-eye, but the individual arrows are inaccurate.)


Accuracy and Precision in Logic Level Modeling and IC Simulation

As described in the SIGDA Newsletter [Vol 20. Number 1, June 1990] a common mistake in evaluation of accurate models is to compare a logic simulation model to a transistor circuit simulation model. This is a comparison of differences in precision, not accuracy. Precision is measured with respect to detail and accuracy is measured with respect to reality. Another reference for this topic is "Logic Level Modelling", by John M. Acken, Encyclopedia of Computer Science and Technology, Vol 36, 1997, page 281-306.


Quantifying Accuracy and Precision

Ideally a measurement device is both accurate and precise, with measurements all close to and tightly clustered around the known value.

The accuracy and precision of a measurement process is usually established by repeatedly measuring some traceable reference standard. Such standards are defined in the International System of Units and maintained by national standards organizations such as the National Institute of Standards and Technology.

Precision is usually characterized in terms of the standard deviation of the measurements, sometimes called the measurement process's standard error. The interval defined by the standard deviation is the 68.3% ("one sigma") confidence interval of the measurements. If enough measurements have been made to accurately estimate the standard deviation of the process, and if the measurement process produces normally distributed errors, then it is likely that 68.3% of the time, the true value of the measured property will lie within one standard deviation, 95.4% of the time it will lie within two standard deviations, and 99.7% of the time it will lie within three standard deviations of the measured value.

This also applies when measurements are repeated and averaged. In that case, the term standard error is properly applied: the precision of the average is equal to the known standard deviation of the process divided by the square root of the number of measurements averaged. Further, the central limit theorem shows that the probability distribution of the averaged measurements will be closer to a normal distribution than that of individual measurements.

With regard to accuracy we can distinguish:

• Repeatability - the variation arising when all efforts are made to keep conditions constant by using the same instrument and operator, and repeating during a short time period; and
• Reproducibility - the variation arising using the same measurement process among different instruments and operators, and over longer time periods.

As stated before, you can be both accurate and precise. For instance, if all your arrows hit the bull's eye of the target, they are all both near the "true value" (accurate) and near one another (precise).

Something to think about: In the NFL, a place kicker makes 9 of 10 field goals, and another makes 6 of 10. Even if the 6 that the second kicker made were straight down the middle and the first kicker just made his in, he is still less accurate and less precise than the first kicker. This differs from the darts example because either you make it or you do not; there are not different levels of points that can be scored.

Active Directory Definition, What is Active Directory

Active Directory is an implementation of LDAP directory services by Microsoft for use in Windows environments. Active Directory allows administrators to assign enterprise-wide policies, deploy programs to many computers, and apply critical updates to an entire organization. An Active Directory stores information and settings relating to an organization in a central, organized, accessible database. Active Directory networks can vary from a small installation with a few hundred objects, to a large installation with millions of objects.

Active Directory was previewed in 1996, released first with Windows 2000, and saw some revision to extend functionality and improve administration in Windows Server 2003.

Active Directory was called NTDS (NT Directory Service) in older Microsoft documents. This name remains in some AD binaries as well.


Active Directory Structure

(Objects)

Active Directory is a directory service used to store information about the network resources across a domain.

An Active Directory (AD) structure is a hierarchical framework of objects. The objects fall into three broad categories — resources (e.g. printers), services (e.g. e-mail), and users (accounts, or users and groups). The AD provides information on the objects, organizes the objects, controls access, and sets security.

Each object represents a single entity — whether a user, a computer, a printer, an application, or a shared data source—and its attributes. Objects can also be containers of other objects. An object is uniquely identified by its name and has a set of attributes—the characteristics and information that the object can contain—defined by a schema, which also determines the kind of objects that can be stored in the AD.

Each attribute object can be used in several different schema class objects. These schema objects exist to allow the schema to be extended or modified when necessary. However, because each schema object is integral to the definition of AD objects, deactivating or changing these objects can have serious consequences because it will fundamentally change the structure of AD itself. A schema object, when altered, will automatically propagate through Active Directory and once it is created it can only be deactivated—not deleted. Changing the schema usually requires a fair amount of planning


Forests, Trees, and Domains

The framework that holds the objects is viewed at a number of levels. At the top of the structure is the Forest - the collection of every object, its attributes and rules (attribute syntax) in the AD. The forest holds one or more transitive, trust-linked Trees. A tree holds one or more Domains and domain trees, again linked in a transitive trust hierarchy. Domains are identified by their DNS name structure, the namespace. A domain has a single DNS name.

The objects held within a domain can be grouped into containers called Organizational Units (OUs). OUs give a domain a hierarchy, ease its administration, and can give a semblance of the structure of the AD's company in organizational or geographical terms. OUs can contain OUs - indeed, domains are containers in this sense - and can hold multiple nested OUs. Microsoft recommends as few domains as possible in AD and a reliance on OUs to produce structure and improve the implementation of policies and administration. The OU is the common level at which to apply group policies, which are AD objects themselves called Group Policy Objects (GPOs), although policies can also be applied to domains or sites (see below). The OU is the lowest level at which administrative powers can be delegated.

As a further subdivision AD supports the creation of Sites, which are physical, rather than logical, groupings defined by one or more IP subnets. Sites distinguish between locations connected by low-speed (e.g. WAN, VPN) and high-speed (e.g. LAN) connections. Sites can contain one or more domains and domains can contain one or more sites. This is important to control network traffic generated by replication.

The actual division of the company's information infrastructure into a hierarchy of one or more domains and top-level OUs is a key decision. Common models are by business, by geographical location, or by IT roles. These models are also often used in combination.


Physical Structure and Replication

Physically the AD information is held on one or more equal peer domain controllers (DCs), replacing the NT PDC/BDC format (although there is a 'more equal' flexible single master operation (FSMO) server for some operations, which can simulate a PDC). Each DC holds a single domain partition and a read-and-write copy of the AD; changes on one computer being synchronized (converged) between all the DC computers by multi-master replication. Servers without AD are called Member Servers.

Unlike earlier versions of Windows which used NetBIOS to communicate, Active Directory is fully integrated with DNS and TCP/IP — indeed DNS is required. To be fully functional, the DNS server must support SRV resource records or service records.

AD replication is 'pull' rather than 'push'. The AD creates a replication topology that uses the defined sites to manage traffic. Intrasite replication is frequent and automatic through the Knowledge Consistency Checker (KCC), while intersite replication is configurable, depending on the quality of each site link - a different 'cost' can be given to each link (e.g. DS3, T1, ISDN etc.) and replication traffic limited, scheduled, and routed accordingly. Replication data may be transitively passed through several sites on same-protocol site link bridges, if the 'cost' is low, although AD automatically costs a direct site-to-site link lower than transitive connections. Site-to-site replication is between a bridgehead server in each site, which then replicates the changes to other DCs within the site.

In a multi-domain forest the AD database becomes partitioned. That is, each domain maintains a list of only those objects that belong in that domain. So, for example, a user created in Domain A would be listed only in Domain A's domain controllers. Global catalog (GC) servers are used to provide a global listing of all objects in the Forest. The Global catalog is held on domain controllers configured as global catalog servers. Global Catalog servers replicate to themselves all objects from all domains and hence, provide a global listing of objects in the forest. However, in order to minimize replication traffic and to keep the GC's database small, only selected attributes of each object are replicated. This is called the partial attribute set (PAS). The PAS can be modified by modifying the schema and marking attributes for replication to the GC.

Replication of Active Directory uses RPCs (Remote Procedure Calls). Between Sites you can also choose to use SMTP for replication, but only for changes in the Schema or Configuration. SMTP cannot be used for replicating the Domain partition. In other words, if a domain exists on both sides of a WAN connection, you must use RPCs for replication.

Although most operations, such as creating a user, are multi-mastered, and can be made by connecting to any available domain controller, some operations are still handled only by designated domain controllers. Microsoft sometimes calls this the Flexible Single Master Operation (FSMO) roles. There are five FSMO roles. Two of these are per forest: There is only one DC in the forest acting as the Schema Master. It holds the master copy of the Schema. There is only one DC in the forest acting as the Domain Naming Master. It authorizes the creation and deletion of domains in the forest. Within each domain there are three further roles. Each domain has a PDC emulator. As its name suggests it provides compatibility with legacy (NT4) DCs and clients. It also functions as the domain master browser, source for time synchronization within the domain, and the single mastering of Group Policies.

Each domain also has a RID Master. The RID Master generates a pool of Relative IDentifiers and allocates them to other DCs in its domain. Each DC can use a RID from its pool whenever it needs to generate a SID (Security IDentifier) for any new security principals object (users, groups or computers) that is created. A SID is a globally unique identifier for a security principal. The RID master is also used to single master the movement of security principals from one domain to another. Finally, each domain has an Infrastructure Master (IM). The IM periodically looks up references to external objects by consulting the global catalog. An example of an 'external object' would be if you added a user from one DomainA to a group in DomainB. As far as Domain B is concerned the user is an external object. The IM is checking to see if any details about that foreign object (such as its distinguished name or SID) have changed.

All these roles can be held by a single DC if necessary. The role of GC and IM are incompatible and should not be on the same machine. The exception to this rule is if there is only one domain in the forest or if all DCs in the domain are configured as GCs. The Domain Naming Master should be the same machine as a GC. These roles can also be transferred. If the current FSMO has failed beyond repair, the roles can be seized at another DC. However, there is no automatic failover. Administrators must manually transfer or seize roles.

The AD is split into three different stores or partitions. Microsoft often refer to these partitions as 'naming contexts'. The 'Schema' partition contains the definition of object classes and attributes within the Forest. The 'Configuration' partition, contains information on the structure of the forest. The 'Domain' partition holds all objects created in that domain. The first two partitions replicate to all domain controllers in the Forest. The Domain partition replicates only to Domain Controllers within its domain. A Partial Attribute Set (PAS) of all objects also replicates to the global catalog.

The AD database, the directory store, in Windows 2000 uses the JET Blue-based Extensible Storage Engine (ESE98), limited to 16 terabytes and 1 billion objects in each domain controller's database (a theoretical limit, only 100 million or so have been tested. NT4's Security Account Manager could support no more that 40,000 objects). Called NTDS.DIT, it has two main tables: the data table and the link table. In Windows 2003 a third main table was added for security descriptor single instancing.

Active Directory Naming

Active Directory supports UNC (\), URL (/), and LDAP URL names for object access. AD internally uses the LDAP version of the X.500 naming structure.

Every object has a Distinguished name (DN), so a printer object called HPLaser3 in the OU Marketing and the domain foo.org, would have the DN: CN=HPLaser3,OU=Marketing,DC=foo,DC=org where CN is common name and DC is domain object class, DNs can have many more than four parts. The object can also have a Canonical name, essentially the DN in reverse, without identifiers, and using slashes: foo.org/Marketing/HPLaser3. To identify the object within its container the Relative distinguished name (RDN) is used: CN=HPLaser3. Each object also has a Globally Unique Identifier (GUID), a unique and unchanging 128-bit string which is used by AD for search and replication. Certain objects also have a User principal name (UPN), an objectname@domain name form.

Active Directory Topic of Trust

To allow users in one domain to access resources in another, AD uses trust. Trust is automatically produced when domains are created. The forest sets the default boundaries of trust, not the domain, and implicit trust is automatic. As well as two-way transitive trust, AD trusts can be shortcut (joins two domains in different trees, transitive, one- or two-way), forest (transitive, one- or two-way), realm (transitive or nontransitive, one- or two-way), or external (nontransitive, one- or two-way) in order to connect to other forests or non-AD domains. AD uses the Kerberos V5 protocol, although NTLM is also supported and web clients use SSL/TLS.

Simply speaking, AD uses trust to allow users in one domain to have access to resources in another domain. The AD trust has a two way trust with its parent. The root of every tree has a two way trust with the Forest Root domain. As a result, every domain in the forest, either explicitly or implicitly, trusts every other domain in the forest. These default trusts cannot be deleted.


Trust relationship is a description of the user access between two domains consisting of a one way and a two way trust.

• One way trust - When one domain allows access to users on another domain, but the other domain does not allow access to users on the first domain.
• Two way trust - When two domains allow access to users on the other domain.
• Trusting domain - The domain that allows access to users on another domain.
• Trusted domain - The domain that is trusted; whose users have access to the trusting domain.
• Transitive trust - A trust that can extend beyond two domains to other trusted domains in the tree.
• Intransitive trust - A one way trust that does not extend beyond two domains.
• Explicit trust - A trust that an admin creates. It is not transitive and is one way only.
• Cross link trust - An explicit trust between domains in different trees or in the same tree when a descendant/ancestor (child/parent) relationship does not exist between the two domains.

Windows 2000 - supports the following types of trusts:

• Two way transitive trusts.
• One way non transistive trusts.
• Additional trusts can be created by administrators. Like a shortcut as example.

References

"Windows Server 2003: Active Directory Infrastructure" (2003). Microsoft Press. ISBN 0-7356-1438-5."

Abbreviation Definition, What is an Abbreviation

Abbreviation (from Latin brevis "short") is strictly a shorter form of a word, but more particularly, an abbreviation is a letter or group of letters, taken from a word or words, and employed to represent them for the sake of brevity. For example, the word "abbreviation" can be abbreviated as "abbr." or "abbrev."

Types of abbreviations

Apart from the common form of shortening one word, there are other types of abbreviations. These include acronym and initialism (including TLA), apocopation (that is, apocope), clipping (phonetics), elision, syncope, syllabic abbreviation, portmanteau.

Syllabic abbreviation

A syllabic abbreviation (SA) is an abbreviation formed from (usually) initial syllables of several words, such as Interpol for International police.

SAs are usually written in lower case, sometimes starting with a capital letter, and are always pronounced as words rather than letter by letter.

SAs should be distinguished from portmanteaux.

Use in different languages
Syllabic abbreviations are not widely used in English or French, but are common in certain languages, like German and Russian.

They prevailed in Germany under the Nazis and in the Soviet Union for naming the plethora of new bureaucratic organizations. For example, Gestapo stands for Geheime Staats-Polizei, or "secret state police". This has given syllabic abbreviations a negative connotation, even though they were used in Germany before the Nazis, e.g., Schupo for Schutzpolizist. Even now Germans call part of their police Kripo for Kriminalpolizei. Syllabic abbreviations were also typical of German language used in the German Democratic Republic, e.g. Stasi for Staatssicherheit ("state security", the secret police & secret service) or Vopo for Volkspolizist ("people's policeman"). Some syllabic abbreviations from Russian that are familiar to English speakers include samizdat and kolkhoz. Orwell's novel 1984 uses syllabic abbreviations like "Engsoc" (=ENGlish SOCialism) to evoke the use of language under the Nazi and Soviet regimes.

East Asian languages whose writing uses Chinese-originated ideograms instead of an alphabet form abbreviations similarly by using key characters from a term or phrase. For example, in Japanese the term for the United Nations, kokusai rengō is often abbreviated to kokuren. Another classic example is shogun. Such abbreviations are called ryakugo in Japanese. SAs are frequently used for names of universities: for instance, Beida for Peking University (Beijing) and Tōdai for the University of Tokyo

Usage of syllabic abbreviations in organisations
Syllabic abbreviations are preferred by the US Navy as it increases readability amidst the large number of initialisms that would otherwise have to fit into the same acronyms. Hence DESRON 6 is used (in the full capital form) to mean "Destroyer Squadron 6," while COMNAVFORLANT would be "Commander, Naval Force (in the) Atlantic."


Style Conventions and Abbreviations

In modern English there are several conventions for abbreviations and the choice may be confusing. The only rule universally accepted is that one should be consistent, and to this end publishers express their preferences in a style guide.

Questions which arise include the following:

• Use of upper or lower case letters. If the original word was capitalised, then the first letter of its abbreviation should retain the capital, for example Lev. for Leviticus. When abbreviating words spelled with lower case letters, there is no consistent rule.

• Use of periods (full stops) and spaces, for example when abbreviating United States, should one write "US", "U.S." or "U. S."? Spaces are generally not used between single letter abbreviations of words in the same phrase, so one almost never encounters "U. S.". In American English, the period is usually added if the abbreviation may be interpreted as a word, though some American writers do not use a period here. Sometimes, periods are used for certain acronyms but not others; a notable instance in American English is to write United States, European Union, and United Nations as U.S., EU, and UN respectively. There is no stop/period between letters of the same word, for example St. and not S.t. for Saint. While users of British English often abbreviate in the same manner, it is more common in formal writing that abbreviations are written with full stops if the word has been cut at the point of abbreviation (e.g., "Street" – "St[reet]" – becomes "St."), but not otherwise (e.g., "Saint" – "S[ain]t" – becomes "St"); a third standard removes the full stops from all abbreviations (e.g., both "Saint" and "Street" become "St"). Thus in the United Kingdom, titles such as "Doctor", "Mister" and "Mis'ess" are commonly abbreviated as "Dr", "Mr", and "Mrs" respectively, but they are also frequently written, as in Canada and the U.S., as "Dr.", "Mr." and "Mrs."

• Acronyms that were originally capitalized (with or without periods) but have since "stood the test of time" by entering the vocabulary as generic words are no longer abbreviated with capital letters nor with any periods—e.g., sonar, radar, lidar, laser, and scuba.

• Whether to add an apostrophe for a plural where the plural is not formed by doubling up the last letter: should one write CDs or CD's? The apostrophe is not needed grammatically but sometimes is added to make it clear that the s is not part of the abbreviation. Because the apostrophe most often represents possession or a contraction, some style guides prefer that it not be used at all with abbreviations, but only with individual letters—"Dot all your i's and cross all your t's!" or "Mind your p's and q's!"—or numbers—"The dyslexic student mixes up his S's and 5's." Thus numbers, such as decades, that are understood to represent other concepts, are not written with apostrophes either—e.g., "The U.S. enjoyed an economic boom in the 1990s and the Roaring ’20s", referring to decades, or "I am going to the bank to exchange four 5's for two 10's", where the 5's and 10's refer to banknotes.

Conventions followed by publications and newspapers:

Publications based in the United States tend to follow the style guides of the Chicago Manual of Style and the Associated Press. The U.S. Government follows a style guide published by the U.S. Government Printing Office.

• There is some inconsistency in abbreviation styles, however, as they are not rigorously defined by style guides. Some two-word abbreviations, like "United Nations", are abbreviated with uppercase letters and periods, and others, like "personal computer" (PC) and "compact disc" (CD), are not; rather, they are typically abbreviated without periods and in uppercase letters. A third variation is to use lowercase letters with periods; this is used by Time Magazine in abbreviating "public relations" (p.r.). Moreover, even three-word abbreviations (most U.S. publications use uppercase abbreviations without periods) are sometimes not consistently abbreviated, even within the same article.

• The New York Times is unique in having a consistent style by always abbreviating with periods: P.C., I.B.M., P.R. This is in contrast with the trend of British publications to completely make do without periods for convenience.

Many British publications follow some of these guidelines in abbreviation:

For the sake of convenience, many British publications, including the BBC and The Guardian, have completely done away with the use of full stops or periods in all abbreviations. These include:

• Social titles, like Ms or Mr (though these would not have had full stops in any case — see above) Capt, Prof, etc.;
• Two-letter abbreviations for countries (US, not U.S.);
• Words are seldom abbreviated with lower case letters (PR, instead of p.r., or pr)
• Abbreviations beyond three letters (full caps for all except initial-isms);
• Names (e.g., FW de Klerk, GB Whiteley, Park JS). A notable exception is the Economist (e.g., Mr F. W. de Klerk)
• Scientific units.

Acronyms are often referred to with only the first letter of the abbreviation capitalised. For instance, the North Atlantic Treaty Organisation can be abbreviated as Nato or NATO, and Severe Acute Respiratory Syndrome as Sars or SARS (compare with laser which has made the full transition to an English word and is rarely capitalised at all). Initialisms (which are similar to acronyms but which are not pronounced as words) are always written in capitals, for instance the British Broadcasting Corporation is abbreviated to BBC, never Bbc.

When abbreviating scientific units, no space is added between the number and unit (e.g., 100mph, 100m, 10cm, 10ºC).

Miscellaneous and general rules

• Plurals are often formed by doubling up the last letter of the abbreviation. Most of these deal with writing and publishing: MS=manuscript, MSS=manuscripts; l=line, ll=lines; p=page, pp=pages; s=section, ss=sections; op.=opus, opp.=opera). This form, derived from Latin is used in Europe in many places: dd=didots. "The following (lines or pages)" is denoted by ff. One example that does not concern printing is hh=hands.

• A doubled letter also appears in abbreviations of some Welsh names, as in Welsh the double "l" is a separate sound: "Ll. George" for (British prime minister) Lloyd George.

• Some titles, such as "Reverend" and "Honourable", are spelt out when preceded by "the", rather than as "Rev." or "Hon." respectively. This is true for most British publications, and some in the United States.

• It is usually advised to spell out the abbreviation where it is new or unfamiliar to the reader (e.g. UNESCO in a magazine about music, because it refers to the United Nations Educational, Scientific and Cultural Organization, whose work does not concern music).

Measurement and Abbreviations

• The SI international system has a clearly defined set of base units, from which other "derived" units may be obtained. The abbreviations, or more accurately "symbols" (using Roman letters (Greek in the case of ohm)) for these units are also clearly defined together with a set of prefixes, themselves symbolised (abbreviated) with Roman letters (Greek in the singular case of micro, µ), denoting powers of ten. The system is internationally recognised. Periods are not used, except as described below. Neither a unit nor its symbol takes "s" for plural.

• In the SI international system of units there should never be a period after or inside the unit, i.e. both 10 k.m. and 10 k.m are wrong - the only correct form is 10 km (only followed with a period when at the end of a sentence).

• Placing a period "within" a unit will alter its meaning, as a period is used in the SI system to form compound units and denotes multiplication. Ideally this period should be raised to the centre of the line, but it is often not. So for instance 5 ms means 5 millisecond(s), whereas 5 m.s means 5 metre.second(s). The "m.s" here is a compound unit formed from the product of two fundamental SI units - metre and second.

• There should always be a (non-breaking) space between the number and the unit - 10A, 15V, and 25km are all incorrect; they should be 10 A, 15 V and 25 km. The case of letters (i.e. upper (capital) or lower) is also an important part of the SI system and the case should never be changed because of a misguided attempt to follow an abbreviation style. 10 S is quite different in meaning, to a scientist or engineer, from 10 s. The former denotes 10 siemens (a unit of conductance), the latter 10 seconds. Units named after people use a symbol of an upper case first letter, e.g. S, Pa, A, V, N, Wb, W, but spelt out in full in lower case, e.g. siemens, pascal, ampere, volt, newton, weber and watt. By contrast g, l, m, s, cd, h represent gramme, litre, metre, second, candela and hectare respectively. The one slight exception to this rule is the symbol for litre is allowed to be L to help avoid confusion with an upper case i or a one in some type styles—i.e. c.f. l and I.

• Likewise the abbreviations of the prefixes denoting powers of ten are case sensitive - m (milli) is a thousandth, M (mega) is a million times, so by inadvertent changes of case one may introduce (in this example) an error of a factor of 1 000 000 000. When written out in full lower case is used for both the prefix and the unit, e.g. megampere for MA, millivolt for mV, nanometre for nm, gigacandela for Gcd.

• The above rules, if followed, ensure that the SI system is always unambiguous, so for instance mK is a millikelvin, MK is a megakelvin, K.m is a kelvin.metre, and km is a kilometre. Forms such as k.m and Km are ill-formed and technically meaningless in the SI system although it may be possible to infer which unit is meant from the context.

Powers of ten prefixes:

• 10²⁴  yotta  Y
• 10²¹  zetta  Z
• 10¹⁸  exa    E
• 10¹⁵  peta   P
• 10¹²  tera   T
• 10⁹  giga   G
• 10⁶  mega   M
• 10³  kilo   k
• 10²  hecto  h
• 10¹  deka   da
• 10^-1  deci   d
• 10^-2  centi  c
• 10^-3  milli  m
• 10^-6  micro  µ
• 10^-9  nano   n
• 10^-12  pico   p
• 10^-15  femto  f
• 10^-18  atto   a
• 10^-21  zepto  z
• 10^-24  yocto  y

History of Abbreviations

After World War II, the British greatly reduced their use of the full stop and other punctuations after abbreviations in at least semi-formal writing, while the Americans more readily kept its use until more recently, and still maintain it more than Britons. The classic example, considered by their American counterparts quite curious, was the maintenance of the internal comma in a British organization of secret agents called the "Special Operations, Executive" – "S.O.E." – which is not found in histories written after about 1960.


But before that, many Britons were more scrupulous at maintaining the French form. In French, the period only follows an abbreviation if the last letter in the abbreviation is not the last letter of its antecedent: "M." is the abbreviation for "monsieur" while "Mme" is that for "Madame" and "Mlle" for "Mademoiselle". Like many other cross-channel linguistic acquisitions, many Britons readily took this up and followed this rule themselves, while the Americans took a simpler rule and applied it rigorously.

Over the years, however, the lack of convention in some style guides has made it difficult to determine which two-word abbreviations should be abbreviated with periods and which should not. The U.S. media tend to abbreviate two-word abbreviations like United States (U.S.), but surprisingly, not personal computer (PC) or television (TV), which is a source of confusion. Many British publications have gradually done away with the use of periods in abbreviations completely.

List of Computing and IT Abbreviations

• /. - Slashdot
• 1GL - First-Generation Programming Language
• 10B2 - 10 Base2
• 10B5 - 10 Base5
• 10B-F - 10 Base-F
• 10B-FB - 10 Base-FB
• 10B-FL - 10 Base-FL
• 10B-FP - 10 Base-FP
• 10B-T - 10 Base-T
• 100B-FX - 100 Base-FX
• 100B-T - 100 Base-T
• 100B-TX - 100 Base-TX
• 100BVG - 100 BaseVG
• 286 - 80286
• 2B1Q - 2 Binary 1 Quaternary
• 2GL - Second-Generation Programming Language
• 3GL - Third-Generation Programming Language
• 386 - 80386
• 486 - 80486
• 4B5BLF - 4 Byte 5 Byte Local Fiber
• 4GL - Fourth-Generation Programming Language
• 5GL - Fifth-Generation Programming Language
• 8B10BLF - 8 Byte 10 Byte Local Fiber
• AA - Anti-Aliasing
• AAA - Authentication Authorization, Accounting
• AABB - Axis Aligned Bounding Box
• AAC - Advanced Audio Coding (audio compression format defined by the MPEG-2 standard)
• AAL - ATM Adaptation Layer
• AALC - ATM Adaptation Layer Connection
• AARP - AppleTalk Address Resolution Protocol
• ABI - Application Binary Interface
• ABM - Asynchronous Balanced Mode
• ABR - Area Border Router
• ABR - Auto Baud - Rate Detect
• ABR - Available Bit Rate
• AC - Alternating Current
• AC - Acoustic Coupler
• ACID - Atomiticy Consistency Isolation Durability
• ACL - Access Control List
• ACL - Active Current Loop
• ACM - Association for Computing Machinery
• ACPI - Advanced Configuration and Power Interface
• ACD - Automatic Call Distributor
• ACF - Advanced Communications Function
• ACF NCP - Advanced Communications Function - Network Control Program
• ACK - ACKnowledgement
• ACR - Allowed Cell Rate
• ACR - Attenuation to Crosstalk Ratio
• AD - Active Directory
• AD - Administrative Domain
• ADC - Analog-To-Digital Converter
• ADC - Apple Display Connector (DVI variant)
• ADB - Apple Desktop Bus
• ADCCP - Advanced Data Communications Control Protocol/Procedures
• ADO - ActiveX Data Objects
• ADSL - Asymmetric Digital Subscriber Line (variant of DSL)
• AE - Adaptive Equalizer
• AES - Advanced Encryption Standard
• AF - Anisotropic Filtering
• AFP - Apple Filing Protocol
• AGP - Accelerated Graphics Port (sometimes used with a suffix indicating the port's bandwidth, like AGP4x)
• AH - Active Hub
• AI - Artificial Intelligence
• AIM - AOL Instant Messenger
• AIX - Advanced Interactive Executive
• Ajax - Asynchronous JavaScript and XML
• AL - Active Link
• AL - Access List
• ALGOL - Algorithmic Language
• ALSA - Advanced Linux Sound Architecture
• ALU - Arithmetic and Logical Unit
• AM - Active Matrix
• AM - Access Method
• AM - Active Monitor
• AMD - Advanced Micro Devices
• AMI - American Megatrends Inc. (BIOS manufacturer)
• AMR - Audio Modem Riser
• ANN - Artificial Neural Network
• ANSI - American National Standards Institute
• ANT - Another Neat Tool
• AoE - ATA over Ethernet
• AOL - America Online
• AOP - Aspect-Oriented Programming
• APCI - Application-Layer Protocol Control Information
• API - Application Programming Interface
• APIC - Advanced Programmable Interrupt Controller
• APIPA - Automatic Private IP Addressing
• APL - A Programming Language
• APS - Accunet Packet Service
• APR - Apache Portable Runtime
• ARM - Advanced RISC Machines
• ARP - Address Resolution Protocol
• ARPA - Address and Routing Parameter Area
• ARPA - Advanced Research Projects Agency (see also DARPA)
• ARPANET - Advanced Research Projects Agency Network
• AS - Access Server
• ASCII - American Standard Code for Information Interchange
• ASG - Abstract Semantic Graph
• ASIC - Application Specific Integrated Circuit
• ASMP (computing) - Asymmetric Multiprocessing
• ASN.1 - Abstract Syntax Notation 1
• ASP - Application Service Provider
• ASP (MS ASP) - Active Server Pages
• AST - Abstract Syntax Tree
• ASSP - Application Specific Standard Product
• AT - Advanced Technology
• AT - Access Time
• AT - Active Terminator
• ATA - Advanced Technology Attachment
• ATAG - Authoring Tool Accessibility Guidelines
• ATAPI - Advanced Technology Attachment Packet Interface
• ATG - Advanced Technology Group
• ATI - Array Technology Industry
• ATM - Asynchronous Transfer Mode
• AT&T - American Telephone & Telegraph
• AVC - Advanced Video Coding
• AVI - Audio Video Interleaved
• AWT - Abstract Windowing Toolkit
• B2B - Business-to-Business
• B2C - Business-to-Consumer
• Bash - Bourne-again shell
• BASIC - Beginner's All-Purpose Symbolic Instruction Code
• BBP - Baseband Processor
• BBS - Bulletin Board System
• BCD - Binary Coded Decimal
• BEEP - Blocks Extensible Exchange Protocol
• BER - Bit Error Rate
• BFD - Binary File Descriptor
• BFS - Breadth-First Search
• BGP - Border Gateway Protocol
• BiDi - Bi-Directional
• bin - binary
• BINAC - Binary Automatic Computer
• BIND - Berkeley Internet Name Daemon
• BIOS - Basic Input Output System
• BJT - Bipolar Junction Transistor
• Blog - Web Log
• BMP - Basic Multilingual Plane
• BNC - Bayonet Neill-Concelman
• BOFH - Bastard Operator From Hell
• BOINC - Berkeley Open Infrastructure for Network Computing
• BOOTP - Bootstrap Protocol
• BPEL - Business Process Execution Language
• BPL - Broadband over Power Lines
• bps - bits per second
• BRR - Business Readiness Rating
• BSA - Business Software Alliance
• BSD - Berkeley Software Distribution (Unix variant)
• BSOD - Blue Screen of Death (MS Windows specific)
• BSS - Block Started by Symbol
• BT - BitTorrent
• BW - Bandwidth
• CA - Certificate Authority
• CAD - Computer-Aided Design
• CAE - Computer-Aided Engineering
• CAID - Computer Aided Industrial Design
• CAI - Computer-Aided Instruction
• CAM - Computer-Aided Manufacturing
• CAPTCHA - Completely Automated Public Turing Test to tell Computers and Humans Apart
• CAQ - Computer Aided Quality
• CASE - Computer-Aided Software Engineering
• cc - C Compiler
• CD - Compact Disc
• CDE - Common Desktop Environment
• CDMA - Code Division Multiple Access
• CDP - Continuous Data Protection
• CD-R - CD-Recordable
• CD-ROM - CD Read-Only Memory
• CD-RW - CD-Rewritable
• CERT - Computer Emergency Response Team
• CFWS - Comment and/or Folding White Space
• CES - Consumer Electronics Show
• CF - Compact Flash
• CFD - Computational Fluid Dynamics
• CFG - Context-Free Grammar
• CFG - Control Flow Graph
• CG - Computer Graphics
• CGA - Color Graphics Array
• CGI - Common Gateway Interface
• CGI - Computer-Generated Imagery
• CGT - Computational Graph Theory
• CHAP - Challenge-Handshake Authentication Protocol
• CHS - Cylinder-Head-Sector
• CIFS - Common Internet Filesystem
• CIM - Common Information Model
• CISC - Complex Instruction Set Computer
• CJK - Chinese, Japanese, and Korean
• CJKV - Chinese, Japanese, Korean, and Vietnamese
• CLI - Command Line Interface
• CLR - Common Language Runtime
• CM - Configuration Management
• CM - Content Management
• CMOS - Complementary Metal-Oxide Semiconductor
• CMS - Content Management System
• CN - Canonical Name
• CN - Common Name
• CNC - Computer Numerical Control
• CNR - Communications and Networking Riser
• COBOL - Common Business-Oriented Language
• COM - Component Object Model
• CORBA - Common Object Request Broker Architecture
• COTS - Commercial Off-The-Shelf
• CPA - Cell Processor Architecture
• CPA - Control Panel Applet
• CPA - Converged Packet Access
• CPAN - Comprehensive Perl Archive Network
• CP/M - Control Program/Monitor
• cps - characters per second
• CPU - Central Processing Unit
• CR - Carriage Return
• CRAN - Comprehensive R Archive Network
• CRC - Cyclic Redundancy Check
• CRLF - Carriage Return Line Feed
• CRM - Customer Relationship Management
• CRT - Cathode Ray Tube
• CS - Cable Select
• CS - Computer Science
• CSE - Computer Science and Engineering
• CSRF - Cross-Site Request Forgery
• CSS - Cascading Style Sheets
• CSS - Content-Scrambling System
• CSS - Closed Source Software
• CSS - Cross-Site Scripting
• CSV - Comma-Separated Values
• CT - Computerized Tomography
• CTAN - Comprehensive TeX Archive Network
• CTCP - Client-To-Client Protocol
• CTI - Computer Telephony Integration
• CTS - Clear To Send
• CTSS - Compatible Time-Sharing System
• CUA - Common User Access
• CVS - Concurrent Versioning System
• DAC - Digital-To-Analog Converter
• DAC - Discretionary Access Control
• DAO - Data Access Objects
• DAO - Disk At Once
• DAP - Directory Access Protocol
• DARPA - Defense Advanced Research Projects Agency
• DAT - Digital Audio Tape
• DB - Database
• DBA - Database Administrator
• DBCS - Double Byte Character Set
• DBMS - Database Management System
• DCC - Direct Client-to-Client
• DCCA - Debian Common Core Alliance
• DCL - Data Control Language
• DCMI - Dublin Core Metadata Initiative
• DCOM - Distributed Component Object Model
• DD - Double Density
• DDE - Dynamic Data Exchange
• DDL - Data Definition Language
• DDoS - Distributed Denial of Service
• DDR - Double Data Rate
• DEC - Digital Equipment Corporation
• DES - Data Encryption Standard
• dev - device
• DFA - Deterministic Finite Automaton
• DFD - Data Flow Diagram
• DFS - Depth-First Search
• DHCP - Dynamic Host Configuration Protocol
• DHTML - Dynamic HTML
• DIMM - Dual Inline Memory Module
• DIN - Deutsches Institut für Normung
• DIP - Dual In-line Package
• DIVX - Digital Video Express
• DKIM - Domain Keys Identified Mail
• DL - Download
• DLL - Dynamic Link Library
• DLP - Digital Light Processing
• DMA - Direct Memory Access
• DMCA - Digital Millennium Copyright Act
• DML - Data Manipulation Language
• DMR - Dennis M. Ritchie
• DN - Distinguished Name
• DND - Drag-and-Drop
• DNS - Domain Name System
• DOCSIS - Data Over Cable Service Interface Specification
• DOM - Document Object Model
• DoS - Denial of Service
• DOS - Disk Operating System
• DP - Dot Pitch
• DPI - Dots Per Inch
• DPMI - DOS Protected Mode Interface
• DPMS - Display Power Management Signaling
• DRAM - Dynamic Random Access Memory
• DRI - Direct Rendering Infrastructure
• DRM - Digital Rights Management
• DRM - Direct Rendering Manager
• DSDL - Document Schema Definition Languages
• DSDM - Dynamic Systems Development Method
• DSL - Digital Subscriber Line
• DSL - Domain-Specific Language
• DSLAM - Digital subscriber line access multiplexer
• DSN - Database Source Name (ODBC)
• DSN - Dataset Name? (OS/390)
• DSP - Digital Signal Processor
• DSSSL - Document Style Semantics and Specification Language
• DTD - Document Type Definition
• DTE - Data Terminal Equipment
• DTP - Desktop Publishing
• DTR - Data Terminal Ready
• DVD - Digital Versatile Disc
• DVD - Digital Video Disc
• DVD-R - DVD-Recordable
• DVD-ROM - DVD-Read Only Memory
• DVD-RW - DVD-Rewritable
• DVI - Digital Visual Interface
• DVR - Digital Video Recorder (see also PVR)
• EAI - Enterprise Application Integration
• EAP - Extensible Authentication Protocol
• EBCDIC - Extended Binary Coded Decimal Interchange Code
• EBML - Extensible Binary Meta Language
• ECC - Elliptic Curve Cryptography
• ECMA - European Computer Manufacturers Association
• EDI - Electronic Data Interchange
• EDO - Extended Data Out
• EDSAC - Electronic Delay Storage Automatic Computer
• EDVAC - Electronic Discrete Variable Automatic Computer
• EEPROM - Electronically-Eraseable Programmable Read-Only Memory
• EFF - Electronic Frontier Foundation
• EFI - Extensible Firmware Interface
• EFM - Eight-to-Fourteen Modulation
• EGA - Enhanced Graphics Array
• EGP - Exterior Gateway Protocol
• eID - electronic ID card
• EIDE - Enhanced IDE
• EIGRP - Enhanced Interior Gateway Routing Protocol
• EISA - Extended Industry Standard Architecture
• ELF - Extremely Low Frequency
• ELF - Executable and Linkable Format
• ELM - Electronic Mail
• EMACS - Editor Macros
• EMS - Expanded Memory Specification
• ENIAC - Electronic Numerical Integrator And Computer
• EOF - End of File
• EOL - End of Life
• EOL - End of Line
• EOM - End of Message
• EPROM - Eraseable Programmable Read-Only Memory
• ERP - Enterprise Resource Planning
• ESCON - Enterprise Systems Connection
• ESD - Electrostatic Discharge
• ETL - Extract, Transform, Load
• ESR - Eric Steven Raymond
• EUC - Extended Unix Code
• EULA - End User License Agreement
• FAP - FORTRAN Assembly Program
• FAT - File Allocation Table
• FAQ - Frequently Asked Questions
• FBDIMM - Fully Buffered Dual Inline Memory Module
• FCB - File Control Block
• FDD - Floppy Disk Drive
• FDDI - Fiber Distributed Data Interface
• FDMA - Frequency-Division Multiple Access
• FEC - Forward Error Correction
• FEMB - Front-End Motherboard
• FET - Field Effect Transistor
• FICON - Fiber Connectivity
• FIFO - First In First Out
• FHS - Filesystem Hierarchy Standard
• FLAC - Free Lossless Audio Codec
• FLOPS - FLoating-Point Operations Per Second
• FLOSS - Free/Libre/Open Source Software
• FOLDOC - Free On-line Dictionary of Computing
• FOSDEM - Free and Open source Software Developers' European Meeting
• FOSI - Formatted Output Specification Instance
• FOSS - Free and Open Source Software
• FPGA - Field Programmable Gate Array
• FPU - Floating Point Unit
• FS - File System
• FSB - Front Side Bus
• FSF - Free Software Foundation
• FSM - Finite State Machine
• FTTC - Fiber To The Curb
• FTTH - Fiber To The Home
• FTTP - Fiber To The Premises
• FTP - File Transfer Protocol
• FQDN - Fully Qualified Domain Name
• FUD - Fear Uncertainty Doubt
• FWS - Folding White Space
• G11N - Globalization
• Gb - Gigabit
• GB - Gigabyte
• GCC - GNU Compiler Collection (formerly GNU C Compiler)
• GCJ - GNU Compiler for Java
• GCR - Group Code Recording
• GDB - GNU Debugger
• GDI - Graphics Device Interface
• GFDL - GNU Free Documentation License
• GIF - Graphics Interchange Format
• GIGO - Garbage In, Garbage Out
• GIMP - GNU Image Manipulation Program
• GIMPS - Great Internet Mersenne Prime Search
• GIS - Geographic Information System
• GLUT - OpenGL Utility Toolkit
• GNOME - GNU Network Object Model Environment
• GNU - GNU's Not Unix
• GPG - GNU Privacy Guard
• GPGPU - General-Purpose Computing on Graphics Processing Units
• GPIB - General-Purpose Instrumentation Bus
• GPL - General Public License
• GPL - General-Purpose Language
• GPRS - General Packet Radio Service
• GPT - GUID PartitionTable
• GPU - Graphics Processing Unit
• GRUB - Grand Unified Boot-Loader
• GSM - Global System for Mobile Communications
• GTK+ - GIMP Toolkit
• GUI - Graphical User Interface
• GUID - Globally Unique IDentifier
• GWT - Google Web Toolkit
• HAL - Hardware Abstraction Layer
• HBA - Host Bus Adapter
• HCI - Human Computer Interaction
• HD - High Density
• HDD - Hard Disk Drive
• HD-DVD - High Definition DVD
• HDL - Hardware Description Language
• HF - High Frequency
• HID - Human Interface Device
• HIG - Human Interface Guidelines
• HIRD - Hurd of Interfaces Representing Depth
• HMA - High Memory Area
• HP - Hewlett-Packard
• HPC - High-Performance Computing
• HPFS - High Performance File System
• HT - Hyper Threading
• HTM - Hierarchical Temporal Memory
• HTML - Hypertext Markup Language
• HTTP - Hypertext Transport Protocol
• HTTPd - Hypertext Transport Protocol Daemon
• HURD - Hird of Unix-Replacing Daemons
• HVD - Holographic Versatile Disc
• Hz - Hertz
• I18N - Internationalization
• IANA - Internet Assigned Numbers Authority
• iBCS - Intel Binary Compatibility Standard
• IBM - International Business Machines
• IC - Integrated Circuit
• ICANN - Internet Corporation for Assigned Names and Numbers
• ICE - In-Circuit Emulator
• ICE - Intrusion Countermeasure Electronics
• ICMP - Internet Control Message Protocol
• ICP - Internet Cache Protocol
• ICT - Information and Communication Technology
• IDE - Integrated Development Environment
• IDE - Integrated Drive Electronics
• IDL - Interface Definition Language
• IE - Internet Explorer
• IEC - International Electrotechnical Commission
• IEEE - Institute of Electrical and Electronics Engineers
• IETF - Internet Engineering Task Force
• IFL - Integrated Facility for Linux
• IGMP - Internet Group Management Protocol
• IGRP - Interior Gateway Routing Protocol
• IHV - Independent Hardware Vendor
• IIOP - Internet Inter-Orb Protocol
• IIS - Internet Information Services
• IM - Instant Messaging
• IMAP - Internet Message Access Protocol
• IME - Input Method Editor
• I/O - Input/Output
• IP - Intellectual Property
• IP - Internet Protocol
• IPC - Inter-Process Communication
• IPL - Initial Program Load
• IPP - Internet Printing Protocol
• IPsec - Internet Protocol security
• IPX - Internetwork Packet Exchange
• IRC - Internet Relay Chat
• IrDA - Infrared Data Association
• IRQ - Interrupt Request
• IS - Information Systems
• ISA - Industry Standard Architechture
• ISAM - Indexed Sequential Access Method
• ISDN - Integrated Services Digital Network
• ISO - International Organization for Standardization
• ISP - Internet Service Provider
• ISPF - Interactive System Productivity Facility
• ISV - Independent Software Vendor
• IT - Information Technology
• ITU - International Telecommunication Union
• J2CE - Java 2 Cryptographic Edition
• J2EE - Java 2 Enterprise Edition
• J2ME - Java 2 Micro Edition
• J2SE - Java 2 Standard Edition
• JAXP - Java API for XML Processing
• JBOD - Just a Bunch of Disks
• JCL - Job Control Language
• JDBC - Java Database Connectivity
• JDK - Java Development Kit
• JDS - Java Desktop System
• JFC - Java Foundation Classes
• JFET - Junction Field-Effect Transistor
• JFS - Journaling Filesystem
• JINI - Jini Is Not Initials
• JIT - Just-In-Time
• JNI - Java Native Interface
• JPEG - Joint Photographic Experts Group
• JRE - Java Runtime Environment
• JS - JavaScript
• JSON - JavaScript Object Notation
• JSP - Jackson Structured Programming
• JSP - JavaServer Pages
• JTAG - Joint Test Action Group
• JVM - Java Virtual Machine
• jwz - Jamie Zawinski
• JMX - Java Management Extentions
• JMS - Java Messaging Service
• JUG - Java Users Group
• JNDI - Java Naming and Directory Interface
• JAXB - Java XML Binding
• JAX-RPC - Java XML for Remote Procedure Calls
• JCP - Java Community Process
• K&R - Kernighan and Ritchie
• KB - Keyboard
• Kb - Kilobit
• KB - Kilobyte
• KB - Knowledge Base
• KDE - K Desktop Environment
• kHz - Kilohertz
• KISS - Keep It Simple, Stupid
• KVM - Keyboard, Video, Mouse
• L10N - Localization
• LAMP - Linux Apache MySQL (Perl, PHP, or Python)
• LAN - Local Area Network
• LBA - Logical Block Addressing
• LCD - Liquid Crystal Display
• LCOS - Liquid Crystal On Silicon
• LDAP - Lightweight Directory Access Protocol
• LE - Logical Extents
• LED - Light-Emitting Diode
• LF - Line Feed
• LF - Low Frequency
• LFS - Linux From Scratch
• lib - library
• LIF - Low Insertion Force
• LIFO - Last In First Out
• LILO - Linux Loader
• LKML - Linux Kernel Mailing List
• LM - LanManager
• LGPL - [GNU] Lesser General Public License
• LOC - Lines of Code
• LPI - Linux Professional Institute
• LSB - Least Significant Bit
• LSB - Linux Standard Base
• LSI - Large-Scale Integration
• LTR - Left-to-Right
• LUG - Linux User Group
• LUN - Logical Unit Number
• LV - Logical Volume
• LVM - Logical Volume Management
• LZW - Lempel-Ziv-Welch
• MAC - Mandatory Access Control
• MAC - Media Access Control
• MAN - Metropolitan Area Network
• MANET - Mobile Ad-Hoc Network
• MAPI - Messaging Application Programming Interface
• Mb - Megabit
• MB - Megabyte
• MBCS - Multi Byte Character Set
• MBR - Master Boot Record
• MCA - Micro Channel Architecture
• MCSA - Microsoft Certified System Administrator
• MCSD - Microsoft Certified System Developer
• MCSE - Microsoft Certified System Engineer
• MDA - Mail Delivery Agent
• MDA - Model-Driven Architecture
• MDA - Monochrome Display Adapter
• MDI - Multiple Document Interface
• ME - [Windows] Millennium Edition
• MF - Medium Frequency
• MFC - Microsoft Foundation Classes
• MFM - Modified Frequency Modulation
• MGPT - Machine Generated Problem Tracking
• MHz - Megahertz
• MIDI - Musical Instrument Digital Interface
• MIMD - Multiple Instruction, Multiple Data
• MIPS - Million Instructions Per Second
• MIPS - Microprocessor without Interlocked Pipeline Stages
• MIS - Management Information Systems
• MISD - Multiple Instruction, Single Data
• MIT - Massachusetts Institute of Technology
• MIME - Multipurpose Internet Mail Extensions
• MMIO - Memory-Mapped I/O
• MMORPG - Massively Multiplayer Online Role-Playing Game
• MMU - Memory Management Unit
• MMX - Multi-Media Extensions
• MNG - Multiple-image Network Graphics
• MoBo - Motherboard
• MOO - MUD Object Oriented
• MOSFET - Metal-Oxide Semiconductor FET
• MOTD - Message Of The Day
• MPAA - Motion Picture Association of America
• MPEG - Motion Pictures (Coding) Experts Group
• MPL - Mozilla Public License
• MPU - Microprocessor Unit
• MS - Memory Stick
• MS - Microsoft
• MSB - Most Significant Bit
• MS-DOS - Microsoft DOS
• MT - Machine Translation
• MTA - Mail Transfer Agent
• MTU - Maximum Transmission nit
• MSA - Mail Submission Agent
• MSDN - Micrsoft Developer Network
• MSI -Medium-Scale Integration
• MUA - Mail User Agent
• MUD - Multi-User Dungeon
• MVC - Model-View-Controller
• MVP - Most Valuable Professional
• MVS - Multiple Virtual Storage
• MX - Mail exchange
• NACK - Negative ACKnowedgement
• NAK - Negative AcKnowedgement Character
• NAS - Network-Attached Storage
• NAT - Network Address Translation
• NCP - NetWare Core Protocol
• NCQ - Native Command Queuing
• NCSA - National Center for Supercomputing Applications
• NDPS - Novell Distributed Print Services
• NDS - Novell Directory Services
• NEP - Network Equipment Provider
• NEXT - Near-End CrossTalk
• NFA - Nondeterministic Finite Automaton
• GNSCB - Next-Generation Secure Computing Base
• NFS - Network Filesystem
• NI - National Instruments
• NIC - Network Interface Card
• NIM - No Internal Message
• NIO - New I/O
• NIST - National Institute of Standards and Technology
• NLP - Natural Language Processing
• NLS - National Language Support
• NP - Non-Deterministic Polynomial-Time
• NPL - Netscape Public License
• NPU - Network Processing Unit
• NS - Netscape
• NSA - National Security Agency
• NSPR - Netscape Portable Runtime
• NMI - Non-Maskable Interrupt
• NNTP - Network News Transfer Protocol
• NOC - Network Operations Center
• NOP - No OPeration
• NOS - Network Operating System
• NSS - Novell Storage Service
• NSS - Network Security Services
• NSS - Name Service Switch
• NT (Windows) - New Technology
• NTFS - NT Filesystem
• NTLM - NT Lan Manager
• NTP - Network Time Protocol
• NUMA - Non-Uniform Memory Access
• NURBS - Nonuniform Rational B-Spline
• NVRAM - Non-Volatile Random Access Memory
• OASIS - Organization for the Advancement of Structured Information Standards
• ODBC - Open Database Connectivity
• OEM - Original Equipment Manufacturer
• OFTC - Open and Free Technology Community
• OLAP - Online Analytical Processing
• OLE - Object Linking and Embedding
• OLED - Organic Light Emitting Diode
• OLTP - Online Transaction Processing
• OMG - Object Management Group
• OO - Object-Oriented
• OO - Open Office
• OOo - OpenOffice.org
• OOP - Object-Oriented Programming
• OPML - Outline Processor Markup Language
• ORB - Object Request Broker
• OS - Open Source
• OS - Operating System
• OSCON - O'Reilly Open Source Convention
• OSDN - Open Source Developer Network
• OSI - Open Source Initiative
• OSI - Open Systems Interconnection
• OSPF - Open Shortest Path First
• OSS - Open Sound System
• OSS - Open-Source Software
• OSS - Operational Support Systems
• OSTG - Open Source Technology Group (formerly OSDN)
• OUI - Organizationally Unique Identifier
• P2P - Peer-To-Peer
• PAN - Personal Area Network
• PAP - Password Authentication Protocol
• PARC - Palo Alto Research Center
• PATA - Parallel ATA
• PC - Personal Computer
• PCB - Printed Circuit Board
• PCB - Process Control Block
• PCI - Peripheral Component Interconnect
• PCIe - PCI Express
• PCMCIA - Personal Computer Memory Card International Association
• PCM - Pulse-Code Modulation
• PCRE - Perl Compatible Regular Expressions
• PD - Public Domain
• PDA - Personal Digital Assistant
• PDF - Portable Document Format
• PDP - Programmed Data Processor
• PE - Physical Extents
• PERL - Practical Extraction and Reporting Language
• PGA - Pin Grid Array
• PGP - Pretty Good Privacy
• PHP - PHP: Hypertext Preprocessor
• PIC - Peripheral Interface Controller
• PID - Proportional-Integral-Derivative
• PID - Process ID
• PIM - Personal Information Manager
• PINE - Program for Internet News & Email
• PIO - Programmed Input/Output
• PKCS - Public Key Cryptography Standards
• PKI - Public Key Infrastructure
• PLC - Power Line Communication
• PLC - Programmable Logic Controller
• PLD - Programmable Logic Device
• PL/I - Programming Language One
• PL/M - Programming Language for Microcomputers
• PL/P - Programming Language for Prime
• PLT - Power Line Telecoms
• PMM - Personal Memory Manager
• PMM - POST Memory Manager
• PNG - Portable Network Graphics
• PnP - Plug-and-Play
• PoE - Power over Ethernet
• POP - Point of Presence
• POP3 - Post Office Protocol v3
• POSIX - Portable Operating System Interface
• POST - Power-On Self Test
• PPC - PowerPC
• PPI - Pixels Per Inch
• PPP - Point-to-Point Protocol
• PPPoA - PPP over ATM
• PPPoE - PPP over Ethernet
• PPTP - Point-to-Point Tunneling Protocol
• PS - PostScript
• PS/2 - Personal System/2
• PSU - Power Supply Unit
• PSVI - Post-Schema-Validation Infoset
• PV - Physical Volume
• PVG - Physical Volume Group
• PVR - Personal Video Recorder
• PXE - Pre Execution Environment
• PXI - PCI Extensions for Instrumentation
• QDR - Quad Data Rate
• QA - Quality Assurance
• QoS - Quality of Service
• QOTD - Quote of the Day
• Qt - Quasar Toolkit
• RACF - Resource Access Control Facility
• RAD - Rapid Application Development
• RADIUS - Remote Authentication Dial In User Service
• RAID - Redundant Array of Inexpensive Disks
• RAIT - Redundant Array of Inexpensive Tapes
• RAM - Random Access Memory
• RARP - Reverse Address Resolution Protocol
• RC - Release Candidate
• RC - Run Commands
• RC - Runtime Configuration
• RCS - Revision Control System
• RDBMS - Relational Database Management System
• RDF - Resource Description Framework
• REFAL - REcursive Functions Algorithmic Language
• REST - Representational State Transfer
• regex - Regular Expression
• RF - Radio Frequency
• RFC - Request For Comments
• RFE - Request For Enhancement
• RFI - Radio Frequency Interference
• RFID - Radio Frequency Identification
• RGB - Red, Green, Blue
• RGBA - Red, Green, Blue, Alpha
• RHL - Red Hat Linux
• RHEL - Red Hat Enterprise Linux
• RIA - Rich Internet Application
• RIAA - Recording Industry Association of America
• RIP - Raster Image Processor
• RIP - Routing Information Protocol
• RISC - Reduced Instruction Set Computer
• RLE - Run-Length Encoding
• RLL - Run Length Limited
• RMI - Remote Method Invocation
• RMS - Richard Matthew Stallman
• ROM - Read Only Memory
• ROMB - Read-Out Motherboard
• RPC - Remote Procedure Call
• RPM - RPM Package Manager
• RSA - Rivest Shamir Adleman
• RSI - Repetitive Strain Injury
• RSS - Rich Site Summary, RDF Site Summary, or Really Simple Syndication
• RTC - Real-Time Clock
• RTL - Right-to-Left
• RTOS - Real Time Operating System
• RTS - Ready To Send
• SAN - Storage Area Network
• SATA - Serial ATA
• SAX - Simple API for XML
• sbin - superuser binary
• SCADA - Supervisory Control And Data Acquisition
• SCID - Source Code in Database
• SCM - Software Configuration Management
• SCP - Secure Copy
• SCPI - Standard Commands for Programmable Instrumentation
• SCSI - Small Computer System Interface
• SD - Secure Digital
• SDDL - Security Descriptor Definition Language
• SDI - Single Document Interface
• SDIO - Secure Digital Input Output
• SDK - Software Development Kit
• SDL - Simple DirectMedia Layer
• SDN - Service Delivery Network
• SDR - Software-Defined Radio
• SDRAM - Synchronous Dynamic Random Access Memory
• SDSL - Symmetric DSL
• SEAL - Semantics-directed Environment Adaptation Language
• SEI - Software Engineering Institute
• SFTP - Secure FTP
• SFTP - Simple File Transfer Protocol
• SFTP - SSH File Transfer Protocol
• SGI - Silicon Graphics, Incorporated
• SGML - Standard Generalized Markup Language
• SHA - Secure Hash Algorithm
• SIGGRAPH - Special Interest Group on Graphics,
• SIMD - Single Instruction, Multiple Data
• SIMM - Single Inline Memory Module
• SIP - Session Initiation Protocol
• SIP - Supplementary Ideographic Plane
• SISD - Single Instruction, Single Data
• SLI - Scalable Link Interface
• SLIP - Serial Line Internet Protocol
• SLM - Service Level Management
• SLOC - Source Lines of Code
• SPMD - Single Program, Multiple Data
• SMA - SubMiniature version A
• SMB - Server Message Block
• SMBIOS - System Management BIOS
• SMC - SMC Networks (company)
• SMIL - Synchronized Multimedia Integration Language
• S/MIME - Secure/Multipurpose Internet Mail Extensions
• SMP - Supplementary Multilingual Plane
• SMP - Symmetric Multi-Processing
• SMS - Short Message Service
• SMT - Simultaneous Multithreading
• SMTP - Simple Mail Transfer Protocol
• SNA - Systems Network Architecture
• SNMP - Simple Network Management Protocol
• SOA - Service-Oriented Architecture
• SOAP - Simple Object Access Protocol
• SoC - System-on-a-Chip
• SO-DIMM - Small Outline DIMM
• SOI - Silicon On Insulator
• SP - Service Pack
• SPA - Single Page Application
• SPF - Sender Policy Framework
• SPI - Stateful Packet Inspection
• SPARC - Scalable Processor Architecture
• SQL - Structured Query Language
• SRAM - Static Random Access Memory
• SSD - Software Specification Document
• SSH - Secure Shell
• SSI - Server Side Includes
• SSI - Single-System Image
• SSI - Small-Scale Integration
• SSID - Service Set Identifier
• SSL - Secure Socket Layer
• SSP - Supplementary Special-purpose Plane
• su - superuser
• SUS - Single UNIX Specification
• SVG - Scalable Vector Graphics
• SVGA - Super Video Graphics Array
• SWT - Stardard Widget Toolkit
• TAO - Track at Once
• TB - Terabyte
• Tcl - Tool Command Language
• TCP - Transmission Control Protocol
• TCP/IP - Transmission Control Protocol/Internet Protocol
• TCU - Telecommunication Control Unit
• TDMA - Time Division Multiple Access
• temp - temporary (variable, file, directory, etc.)
• TEOS - Trusted Email Open Standard
• TFT - Thin Film Transistor
• TI - Texas Instruments
• Tk -
• TLA - Three-Letter Acronym
• TLD - Top-Level Domain
• TLS - Thread-Local Storage
• TLS - Transport Layer Security
• tmp - temporary (variable, file, directory, etc.)
• TNC - Terminal Node Controller
• TNC - Threaded Neill-Concelman
• TSO - Time Sharing Option
• TSP - Traveling Salesman Problem
• TSR - Terminate and Stay Resident
• TTA - True Tap Audio
• TTL - Transistor-Transistor Logic
• TTL - Time To Live
• TTS - Text-to-Speech
• TTY - Teletype
• TUCOWS - The Ultimate Collection of Winsock Software
• TUG - TeX Users Group
• UAAG - User Agent Accessibility Guidelines
• UART - Universal Asynchronous Receiver Transmitter
• UCS - Universal Character Set
• UDDI - Universal Description, Discovery, and Integration
• UDMA - Ultra DMA
• UDP - User Datagram Protocol
• UE - User Experience
• UEFI - Unified Extensible Firmware Interface
• UHF - Ultra High Frequency
• UI - User Interface
• UL - Upload
• ULA - Uncommitted Logic Array
• UMA - Upper Memory Area
• UMB - Upper Memory Block
• UML - Unified Modeling Language
• UML - User-Mode Linux
• UMPC - Ultra-Mobile Personal Computer
• UNC - Universal Naming Convention
• UPS - Uninterruptible Power Supply
• URI - Uniform Resource Identifier
• URL - Uniform Resource Locator
• URN - Uniform Resource Name
• USB - Universal Serial Bus
• usr - user
• USR - U.S. Robotics
• UTC - Coordinated Universal Time
• UTF - Unicode Transformation Format
• UUCP - Unix to Unix Copy
• UUID - Universally Unique Identifier
• UVC - Universal Virtual Computer
• var - variable
• VAX - Virtual Address eXtension
• VCPI - Virtual Control Program Interface
• VR - Virtual Reality
• VRML - Virtual Reality Modeling Language
• VB - Visual Basic
• VBA - Visual Basic for Applications
• VBS - Visual Basic Script
• VESA - Video Electronics Standards Association
• VFAT - Virtual FAT
• VFS - Virtual File System
• VG - Volume Group
• VGA - Video Graphics Array
• VHF - Very High Frequency
• VLB - Vesa Local Bus
• VLF - Very Low Frequency
• VLSI - Very-Large-Scale Integration
• VM - Virtual Machine
• VM - Virtual Memory
• VOD - Video On Demand
• VoIP - Voice over IP
• VPN - Virtual Private Network
• VPU - Visual Processing Unit
• VSAM - Virtual Storage Access Method
• VSAT - Very Small Aperture Terminal
• VT - Video Terminal?
• VTAM - Virtual Telecommunications Access Method
• W3C - World Wide Web Consortium
• WAFS - Wide Area File Services
• WAI - Web Accessibility Initiative
• WAIS - Wide Area Information Server
• WAN - Wide Area Network
• WAP - Wireless Access Point
• WAP - Wireless Application Protocol
• WAV - WAVEform audio format
• WBEM - Web-Based Enterprise Management
• WCAG - Web Content Accessibility Guidelines
• WCF - Windows Communication Foundation
• WDM - Wavelength Division Multiplexing
• WebDAV - WWW Distributed Authoring and Versioning
• WEP - Wired Equivalent Privacy
• Wi-Fi - Wireless Fidelity
• WiMAX - Worldwide Interoperability for Microwave Access
• WinFS - Windows Future Storage
• WINS- Windows Internet Naming Service
• WLAN - Wireless Local Area Network
• WMA - Windows Media Audio
• WOL - Wake-on-LAN
• WOM - Wake-on-Modem
• WOR - Wake-on-Ring
• WPA - Wi-Fi Protected Access
• WPAN - Wireless Personal Area Network
• WPF - Windows Presentation Foundation
• WSDL - Web Services Description Language
• WSFL - Web Services Flow Language
• WUSB - Wireless Universal Serial Bus
• WWAN - Wireless Wide Area Network
• WWID - World Wide Identifier
• WWN - World Wide Name
• WWW - World Wide Web
• WYSIWYG - What You See Is What You Get
• WZC - Wireless Zero Configuration
• XAG - XML Accessibility Guidelines
• XAML - eXtensible Application Markup Language
• XDM - X Window Display Manager
• XDMCP - X Display Manager Control Protocol
• XCBL - XML Common Business Library
• XHTML - eXtensible Hypertext Markup Language
• XML - eXtensible Markup Language
• XMMS - X Multimedia System
• XMPP - eXtensible Messaging and Presence Protocol
• XMS - Extended Memory Specification
• XNS - Xerox Network Services
• XP - Cross-Platform
• XP - Extreme Programming
• XPCOM - Cross Platform Component Object Model
• XPI - Cross Platform Installer
• XPIDL - Cross Platform IDL
• XSD - XML Schema Definition
• XSL - eXtensible Stylesheet Language
• XSL-FO - eXtensible Stylesheet Language Formatting Objects
• XSLT - XSL Transformations
• XSS - Cross Site Scripting
• XTF - Extensible Tag Framework
• XUL - XML-based User-interface Language
• Y2K - Year Two Thousand
• YACC - Yet Another Compiler Compiler
• YAML - YAML Ain't Markup Language
• YAST - Yet Another Setup Tool
• ZCAV - Zone Constant Angular Velocity
• ZCS - Zero Code Suppression
• ZIF - Zero Insertion Force
• ZIFS - Zero Insertion Force Socket
• ZISC - Zero Instruction Set Computer
• ZOPE - Z Object Publishing Environment
• ZMA - Zone Multicast Address