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117-426: TARGA is an acronym for T ruevision A dvanced R aster G raphics A dapter ; TGA is an initialism for T ruevision G raphics A dapter . TGA files commonly have the extension ".tga" on PC DOS / Windows systems and macOS (older Macintosh systems use the "TPIC" type code ). The format itself permits any pixel bit depth up to 255, of which up to 15 bits can be dedicated to an alpha channel ; however,

234-428: A numeronym . For example, "i18n" abbreviates " internationalization ", a computer-science term for adapting software for worldwide use; the "18" represents the 18 letters that come between the first and the last in "internationalization". Similarly, "localization" can be abbreviated "l10n"; " multilingualization " "m17n"; and " accessibility " "a11y". In addition to the use of a specific number replacing that many letters,

351-645: A single word ("television" or "transvestite", for instance), and is in general spelled without punctuation (except in the plural). Although "PS" stands for the single English word " postscript " or the Latin postscriptum , it is often spelled with periods ("P.S.") as if parsed as Latin post scriptum instead. The slash ('/', or solidus ) is sometimes used to separate the letters in an acronym, as in "N/A" ("not applicable, not available") and "c/o" ("care of"). Inconveniently long words used frequently in related contexts can be represented according to their letter count as

468-400: A word mark set at their high-order (lowest-addressed) position. When an operation such as addition is performed, the processor begins at the low-order positions at the high addresses of the two fields and works its way down to the high-order. Another important attribute of a byte being part of a "field" is its "significance". These attributes of the parts of a field play an important role in

585-507: A 1940 translation of a novel by the German writer Lion Feuchtwanger . It is an unsettled question in English lexicography and style guides whether it is legitimate to use the word acronym to describe forms that use initials but are not pronounced as a word. While there is plenty of evidence that acronym is used widely in this way, some sources do not acknowledge this usage, reserving

702-481: A 32-bit base address of the segment stored in little-endian order, but in four nonconsecutive bytes, at relative positions 2, 3, 4 and 7 of the descriptor start. Hardware description languages (HDLs) used to express digital logic often support arbitrary endianness, with arbitrary granularity. For example, in SystemVerilog , a word can be defined as little-endian or big-endian. The recognition of endianness

819-603: A TGA file contains a footer, it is likely to be a TGA version 2 file. The footer is the final 26 bytes of the file, of which the last 18 are constant. The older version of the TGA file format specification taken from the Appendix C of the Truevision Technical Guide states that run-length encoded (RLE) packets may cross scan lines: "For the run length packet, the header is followed by a single color value, which

936-591: A consecutive sequence of bytes and represents a "simple data value" which – at least potentially – can be manipulated by one single hardware instruction . On most systems, the address of a multi-byte simple data value is the address of its first byte (the byte with the lowest address). There are exceptions to this rule – for example, the Add instruction of the IBM 1401 addresses variable-length fields at their low-order (highest-addressed) position with their lengths being defined by

1053-625: A different meaning. Medical literature has been struggling to control the proliferation of acronyms, including efforts by the American Academy of Dermatology. Acronyms are often taught as mnemonic devices: for example the colors of the rainbow are ROY G. BIV (red, orange, yellow, green, blue, indigo, violet). They are also used as mental checklists: in aviation GUMPS stands for gas-undercarriage-mixture-propeller-seat belts. Other mnemonic acronyms include CAN SLIM in finance, PAVPANIC in English grammar, and PEMDAS in mathematics. It

1170-472: A little-endian should start with FF FE 00 00 . Application binary data formats, such as MATLAB .mat files, or the .bil data format, used in topography, are usually endianness-independent. This is achieved by storing the data always in one fixed endianness or carrying with the data a switch to indicate the endianness. An example of the former is the binary XLS file format that is portable between Windows and Mac systems and always little-endian, requiring

1287-781: A medial decimal point . Particularly in British and Commonwealth English , all such punctuation marking acronyms and other capitalized abbreviations is now uncommon and considered either unnecessary or incorrect. The presence of all-capital letters is now thought sufficient to indicate the nature of the UK , the EU , and the UN . Forms such as the U.S.A. for "the United States of America " are now considered to indicate American or North American English . Even within those dialects, such punctuation

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1404-547: A number of hardware architectures where floating-point numbers are represented in big-endian form while integers are represented in little-endian form. There are ARM processors that have mixed-endian floating-point representation for double-precision numbers: each of the two 32-bit words is stored as little-endian, but the most significant word is stored first. VAX floating point stores little-endian 16-bit words in big-endian order. Because there have been many floating-point formats with no network standard representation for them,

1521-421: A number system, the value of a digit which it contributes to the whole number is determined not only by its value as a single digit, but also by the position it holds in the complete number, called its significance. These positions can be mapped to memory mainly in two ways: In these expressions, the term "end" is meant as the extremity where the big resp. little significance is written first , namely where

1638-407: A period when the letters are pronounced individually, as in " K.G.B. ", but not when pronounced as a word, as in " NATO ". The logic of this style is that the pronunciation is reflected graphically by the punctuation scheme. When a multiple-letter abbreviation is formed from a single word, periods are in general not used, although they may be common in informal usage. "TV", for example, may stand for

1755-483: A processor treats data accesses. Instruction accesses (fetches of instruction words) on a given processor may still assume a fixed endianness, even if data accesses are fully bi-endian, though this is not always the case, such as on Intel's IA-64 -based Itanium CPU, which allows both. Some nominally bi-endian CPUs require motherboard help to fully switch endianness. For instance, the 32-bit desktop-oriented PowerPC processors in little-endian mode act as little-endian from

1872-436: A setting which allows for switchable endianness in data fetches and stores, instruction fetches, or both; those instruction set architectures are referred to as bi-endian . Architectures that support switchable endianness include PowerPC / Power ISA , SPARC V9, ARM versions 3 and above, DEC Alpha , MIPS , Intel i860 , PA-RISC , SuperH SH-4 , IA-64 , C-Sky , and RISC-V . This feature can improve performance or simplify

1989-406: A single byte, so the complexity of the hardware is not affected by the byte ordering. Addition, subtraction, and multiplication start at the least significant digit position and propagate the carry to the subsequent more significant position. On most systems, the address of a multi-byte value is the address of its first byte (the byte with the lowest address). The implementation of these operations

2106-436: A single word, such as NATO (as distinct from B-B-C )" but adds later "In everyday use, acronym is often applied to abbreviations that are technically initialisms, since they are pronounced as separate letters." The Chicago Manual of Style acknowledges the complexity ("Furthermore, an acronym and initialism are occasionally combined (JPEG), and the line between initialism and acronym is not always clear") but still defines

2223-515: A twentieth-century phenomenon. Linguist David Wilton in Word Myths: Debunking Linguistic Urban Legends claims that "forming words from acronyms is a distinctly twentieth- (and now twenty-first-) century phenomenon. There is only one known pre-twentieth-century [English] word with an acronymic origin and it was in vogue for only a short time in 1886. The word is colinderies or colinda , an acronym for

2340-491: A word in a register to the opposite endianness, that is, they swap the order of the bytes in a 16-, 32- or 64-bit word. Recent Intel x86 and x86-64 architecture CPUs have a MOVBE instruction ( Intel Core since generation 4, after Atom ), which fetches a big-endian format word from memory or writes a word into memory in big-endian format. These processors are otherwise thoroughly little-endian. There are also devices which use different formats in different places. For instance,

2457-471: A word, an abbreviation is not an acronym." In contrast, some style guides do support it, whether explicitly or implicitly. The 1994 edition of Merriam-Webster's Dictionary of English Usage defends the usage on the basis of a claim that dictionaries do not make a distinction. The BuzzFeed style guide describes CBS and PBS as "acronyms ending in S". Acronymy, like retronymy , is a linguistic process that has existed throughout history but for which there

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2574-677: A word. American English dictionaries such as Merriam-Webster , Dictionary.com's Random House Webster's Unabridged Dictionary and the American Heritage Dictionary as well as the British Oxford English Dictionary and the Australian Macquarie Dictionary all include a sense in their entries for acronym equating it with initialism , although The American Heritage Dictionary criticizes it with

2691-572: Is a subset with a narrower definition: an initialism pronounced as a word rather than as a sequence of letters. In this sense, NASA / ˈ n æ s ə / is an acronym but USA / j uː ɛ s ˈ eɪ / is not. The broader sense of acronym , ignoring pronunciation, is its original meaning and in common use. Dictionary and style-guide editors dispute whether the term acronym can be legitimately applied to abbreviations which are not pronounced as words, and they do not agree on acronym spacing , casing , and punctuation . The phrase that

2808-594: Is a direct representation of grayscale data. The pixel depth is 8 bits for images of this type. Color map specification (field 4) has three subfields: In case that not the entire color map is actually used by the image, a non-zero first entry index allows to store only a required part of the color map in the file. Image specification (field 5) has six subfields: Bit 4 of the image descriptor byte indicates right-to-left pixel ordering if set. Bit 5 indicates an ordering of top-to-bottom. Otherwise, pixels are stored in bottom-to-top, left-to-right order. Version 1.0 of

2925-509: Is a feature supported by numerous computer architectures that feature switchable endianness in data fetches and stores or for instruction fetches. Other orderings are generically called middle-endian or mixed-endian . Big-endianness is the dominant ordering in networking protocols, such as in the Internet protocol suite , where it is referred to as network order , transmitting the most significant byte first. Conversely, little-endianness

3042-488: Is a question about how to pluralize acronyms. Often a writer will add an 's' following an apostrophe, as in "PC's". However, Kate L. Turabian 's A Manual for Writers of Research Papers, Theses, and Dissertations , writing about style in academic writings, allows for an apostrophe to form plural acronyms "only when an abbreviation contains internal periods or both capital and lowercase letters". Turabian would therefore prefer "DVDs" and "URLs" but "Ph.D.'s". The style guides of

3159-421: Is accessed first for division and comparison . See § Calculation order . When character (text) strings are to be compared with one another, e.g. in order to support some mechanism like sorting , this is very frequently done lexicographically where a single positional element (character) also has a positional value. Lexicographical comparison means almost everywhere: first character ranks highest – as in

3276-399: Is assumed to be repeated the number of times specified in the header. The packet may cross scan lines (begin on one line and end on the next)". However, page 24 of the TGA v2.0 specification states the exact opposite: "Run-length Packets should never encode pixels from more than one scan line . Even if the end of one scan line and the beginning of the next contain pixels of the same value,

3393-721: Is becoming increasingly uncommon. Some style guides , such as that of the BBC , no longer require punctuation to show ellipsis ; some even proscribe it. Larry Trask , American author of The Penguin Guide to Punctuation , states categorically that, in British English , "this tiresome and unnecessary practice is now obsolete." Nevertheless, some influential style guides , many of them American , still require periods in certain instances. For example, The New York Times Manual of Style and Usage recommends following each segment with

3510-430: Is called a byte. Larger groups comprise two or more bytes, for example, a 32-bit word contains four bytes. There are two possible ways a computer could number the individual bytes in a larger group, starting at either end. Both types of endianness are in widespread use in digital electronic engineering. The initial choice of endianness of a new design is often arbitrary, but later technology revisions and updates perpetuate

3627-411: Is common for grammatical contractions (e.g. don't , y'all , and ain't ) and for contractions marking unusual pronunciations (e.g. a'ight , cap'n , and fo'c'sle for "all right", "captain", and "forecastle"). By the early twentieth century, it was standard to use a full stop/period/point , especially in the cases of initialisms and acronyms. Previously, especially for Latin abbreviations , this

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3744-631: Is especially important for paper media, where no search utility is available to find the first use.) It also gives students a convenient review list to memorize the important acronyms introduced in a textbook chapter. Expansion at first use and abbreviation keys originated in the print era, but they are equally useful for electronic text . While acronyms provide convenience and succinctness for specialists, they often degenerate into confusing jargon . This may be intentional, to exclude readers without domain-specific knowledge. New acronyms may also confuse when they coincide with an already existing acronym having

3861-464: Is generally said as two letters, but IPsec for Internet Protocol Security is usually pronounced as / ˌ aɪ ˈ p iː s ɛ k / or / ˈ ɪ p s ɛ k / , along with variant capitalization like "IPSEC" and "Ipsec". Pronunciation may even vary within a single speaker's vocabulary, depending on narrow contexts. As an example, the database programming language SQL is usually said as three letters, but in reference to Microsoft's implementation

3978-405: Is identified and accessed in hardware and software by its memory address . If the total number of bytes in memory is n , then addresses are enumerated from 0 to n  − 1. Computer programs often use data structures or fields that may consist of more data than can be stored in one byte. In the context of this article where its type cannot be arbitrarily complicated, a "field" consists of

4095-406: Is important when reading a file or filesystem created on a computer with different endianness. Fortran sequential unformatted files created with one endianness usually cannot be read on a system using the other endianness because Fortran usually implements a record (defined as the data written by a single Fortran statement) as data preceded and succeeded by count fields, which are integers equal to

4212-481: Is in principle a 16-bit little-endian system. The instructions to convert between floating-point and integer values in the optional floating-point processor of the PDP-11/45, PDP-11/70, and in some later processors, stored 32-bit "double precision integer long" values with the 16-bit halves swapped from the expected little-endian order. The UNIX C compiler used the same format for 32-bit long integers. This ordering

4329-539: Is known as PDP-endian . UNIX was one of the first systems to allow the same code to be compiled for platforms with different internal representations. One of the first programs converted was supposed to print out Unix , but on the Series/1 it printed nUxi instead. A way to interpret this endianness is that it stores a 32-bit integer as two little-endian 16-bit words, with a big-endian word ordering: Segment descriptors of IA-32 and compatible processors keep

4446-434: Is marginally simpler using little-endian machines where this first byte contains the least significant digit. Comparison and division start at the most significant digit and propagate a possible carry to the subsequent less significant digits. For fixed-length numerical values (typically of length 1,2,4,8,16), the implementation of these operations is marginally simpler on big-endian machines. Some big-endian processors (e.g.

4563-459: Is not uncommon for acronyms to be cited in a kind of false etymology , called a folk etymology , for a word. Such etymologies persist in popular culture but have no factual basis in historical linguistics , and are examples of language-related urban legends . For example, " cop " is commonly cited as being derived, it is presumed, from "constable on patrol", and " posh " from " port outward, starboard home ". With some of these specious expansions,

4680-427: Is primarily expressed as big-endian (BE) or little-endian (LE), terms introduced by Danny Cohen into computer science for data ordering in an Internet Experiment Note published in 1980. The adjective endian has its origin in the writings of 18th century Anglo-Irish writer Jonathan Swift . In the 1726 novel Gulliver's Travels , he portrays the conflict between sects of Lilliputians divided into those breaking

4797-442: Is redirected to the corresponding address and unaligned access is not allowed. ARMv6 introduces BE-8 or byte-invariant mode, where access to a single byte works as in little-endian mode, but accessing a 16-bit, 32-bit or (starting with ARMv8) 64-bit word results in a byte swap of the data. This simplifies unaligned memory access as well as memory-mapped access to registers other than 32-bit. Many processors have instructions to convert

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4914-475: Is the dominant ordering for processor architectures ( x86 , most ARM implementations, base RISC-V implementations) and their associated memory. File formats can use either ordering; some formats use a mixture of both or contain an indicator of which ordering is used throughout the file. Computer memory consists of a sequence of storage cells (smallest addressable units); in machines that support byte addressing , those units are called bytes . Each byte

5031-415: Is traditionally pronounced like the word sequel . In writing for a broad audience, the words of an acronym are typically written out in full at its first occurrence within a given text. Expansion At First Use (EAFU) benefits readers unfamiliar with the acronym. Another text aid is an abbreviation key which lists and expands all acronyms used, a reference for readers who skipped past the first use. (This

5148-527: The 6809 and the 68000 series of processors use the big-endian format. Solely big-endian architectures include the IBM z/Architecture and OpenRISC . The PDP-11 minicomputer, however, uses little-endian byte order, as does its VAX successor. The Datapoint 2200 used simple bit-serial logic with little-endian to facilitate carry propagation . When Intel developed the 8008 microprocessor for Datapoint, they used little-endian for compatibility. However, as Intel

5265-682: The Altera Nios II , the Atmel AVR , the Andes Technology NDS32, the Qualcomm Hexagon , and many other processors and processor families are also little-endian. The Intel 8051 , unlike other Intel processors, expects 16-bit addresses for LJMP and LCALL in big-endian format; however, xCALL instructions store the return address onto the stack in little-endian format. Some instruction set architectures feature

5382-516: The Colonial and Indian Exposition held in London in that year." However, although acronymic words seem not to have been employed in general vocabulary before the twentieth century (as Wilton points out), the concept of their formation is treated as effortlessly understood (and evidently not novel) in an Edgar Allan Poe story of the 1830s, " How to Write a Blackwood Article ", which includes

5499-650: The Cray T3E ). IBM AIX and IBM i run in big-endian mode on bi-endian Power ISA; Linux originally ran in big-endian mode, but by 2019, IBM had transitioned to little-endian mode for Linux to ease the porting of Linux software from x86 to Power. SPARC has no relevant little-endian deployment, as both Oracle Solaris and Linux run in big-endian mode on bi-endian SPARC systems, and can be considered big-endian in practice. ARM, C-Sky, and RISC-V have no relevant big-endian deployments, and can be considered little-endian in practice. The term bi-endian refers primarily to how

5616-463: The Intel Fortran compiler supports the non-standard CONVERT specifier when opening a file, e.g.: OPEN ( unit , CONVERT = 'BIG_ENDIAN' ,...) . Other compilers have options for generating code that globally enables the conversion for all file IO operations. This permits the reuse of code on a system with the opposite endianness without code modification. On most systems,

5733-623: The Modern Language Association and American Psychological Association prohibit apostrophes from being used to pluralize acronyms regardless of periods (so "compact discs" would be "CDs" or "C.D.s"), whereas The New York Times Manual of Style and Usage requires an apostrophe when pluralizing all abbreviations regardless of periods (preferring "PC's, TV's and VCR's"). Possessive plurals that also include apostrophes for mere pluralization and periods appear especially complex: for example, "the C.D.'s' labels" (the labels of

5850-539: The Restoration witticism arranging the names of some members of Charles II 's Committee for Foreign Affairs to produce the "CABAL" ministry . OK , a term of disputed origin, dates back at least to the early nineteenth century and is now used around the world. Acronyms are used most often to abbreviate names of organizations and long or frequently referenced terms. The armed forces and government agencies frequently employ acronyms; some well-known examples from

5967-454: The XDR standard uses big-endian IEEE 754 as its representation. It may therefore appear strange that the widespread IEEE 754 floating-point standard does not specify endianness. Theoretically, this means that even standard IEEE floating-point data written by one machine might not be readable by another. However, on modern standard computers (i.e., implementing IEEE 754), one may safely assume that

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6084-480: The "belief" that the etymology is acronymic has clearly been tongue-in-cheek among many citers, as with "gentlemen only, ladies forbidden" for " golf ", although many other (more credulous ) people have uncritically taken it for fact. Taboo words in particular commonly have such false etymologies: " shit " from "ship/store high in transit" or "special high-intensity training" and " fuck " from "for unlawful carnal knowledge", or "fornication under consent/command of

6201-463: The 160-character SMS limit, and to save time, acronyms such as "GF" ("girlfriend"), "LOL" ("laughing out loud"), and "DL" ("download" or "down low") have become popular. Some prescriptivists disdain texting acronyms and abbreviations as decreasing clarity, or as failure to use "pure" or "proper" English. Others point out that languages have always continually changed , and argue that acronyms should be embraced as inevitable, or as innovation that adapts

6318-461: The 18 letters between the initial "i" and the final "n"). Authors of expository writing will sometimes capitalize or otherwise distinctively format the initials of the expansion for pedagogical emphasis (for example, writing: "the onset of Congestive Heart Failure (CHF)" or "the onset of c ongestive h eart f ailure (CHF)"). Capitalization like this, however, conflicts with the convention of English orthography, which generally reserves capitals in

6435-675: The BQ27421 Texas Instruments battery gauge uses the little-endian format for its registers and the big-endian format for its random-access memory . SPARC historically used big-endian until version 9, which is bi-endian. Similarly early IBM POWER processors were big-endian, but the PowerPC and Power ISA descendants are now bi-endian. The ARM architecture was little-endian before version 3 when it became bi-endian. Although many processors use little-endian storage for all types of data (integer, floating point), there are

6552-466: The British press may render it "Nato"), but uses lower case in " Unicef " (from "United Nations International Children's Emergency Fund") because it is more than four letters, and to style it in caps might look ungainly (flirting with the appearance of "shouting capitals"). While abbreviations typically exclude the initials of short function words (such as "and", "or", "of", or "to"), this is not always

6669-495: The C11 standard and commonly used in code interacting with hardware. Some operations in positional number systems have a natural or preferred order in which the elementary steps are to be executed. This order may affect their performance on small-scale byte-addressable processors and microcontrollers . However, high-performance processors usually fetch multi-byte operands from memory in the same amount of time they would have fetched

6786-720: The IBM System/360 and its successors) contain hardware instructions for lexicographically comparing varying length character strings . The normal data transport by an assignment statement is in principle independent of the endianness of the processor. Many historical and extant processors use a big-endian memory representation, either exclusively or as a design option. The IBM System/360 uses big-endian byte order, as do its successors System/370 , ESA/390 , and z/Architecture . The PDP-10 uses big-endian addressing for byte-oriented instructions. The IBM Series/1 minicomputer uses big-endian byte order. The Motorola 6800 / 6801,

6903-434: The TGA specification was very basic, and many developers had a need to store more information, and so opted to add on extra sections to their files, specific to their application only. In Version 2.0 of the specification, these application-specific enhancements/extras are supported by the developer area. Only the offset and size of the developer area are relevant to the spec, and developers are free to add whatever they want in

7020-564: The U.S. Navy, is "COMCRUDESPAC", which stands for "commander, cruisers destroyers Pacific"; it is also seen as "ComCruDesPac". Inventors are encouraged to anticipate the formation of acronyms by making new terms "YABA-compatible" ("yet another bloody acronym"), meaning the term's acronym can be pronounced and is not an offensive word: "When choosing a new name, be sure it is 'YABA-compatible'." Acronym use has been further popularized by text messaging on mobile phones with short message service (SMS), and instant messenger (IM). To fit messages into

7137-560: The United States are among the " alphabet agencies " (jokingly referred to as " alphabet soup ") created under the New Deal by Franklin D. Roosevelt (himself known as "FDR"). Business and industry also coin acronyms prolifically. The rapid advance of science and technology also drives the usage, as new inventions and concepts with multiword names create a demand for shorter, more pronounceable names. One representative example, from

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7254-411: The acronym may use normal case rules, e.g. it would appear generally in lower case, but with an initial capital when starting a sentence or when in a title. Once knowledge of the words underlying such an acronym has faded from common recall, the acronym may be termed an anacronym . Examples of anacronyms are the words " scuba ", " radar ", and " laser ". The word "an acro nym" should not be confused with

7371-545: The acronym stands for is called its expansion . The meaning of an acronym includes both its expansion and the meaning of its expansion. The word acronym is formed from the Greek roots akro- , meaning 'height, summit, or tip', and -nym , 'name'. This neoclassical compound appears to have originated in German , with attestations for the German form Akronym appearing as early as 1921. Citations in English date to

7488-421: The address of a multi-byte value is the address of its first byte (the byte with the lowest address); little-endian systems of that type have the property that, for sufficiently low data values, the same value can be read from memory at different lengths without using different addresses (even when alignment restrictions are imposed). For example, a 32-bit memory location with content 4A 00 00 00 can be read at

7605-590: The adoption of acronyms was modern warfare, with its many highly technical terms. While there is no recorded use of military acronyms dating from the American Civil War (acronyms such as "ANV" for " Army of Northern Virginia " post-date the war itself), they became somewhat common in World War I , and by World War II they were widespread even in the slang of soldiers, who referred to themselves as G.I.s . The widespread, frequent use of acronyms across

7722-506: The apostrophe should be reserved for the possessive ("the TV's antenna"). In some languages, the convention of doubling the letters in the acronym is used to indicate plural words: for example, the Spanish EE.UU. , for Estados Unidos ('United States'). This old convention is still sometimes followed for a limited number of English abbreviations, such as SS. for Saints , pp. for

7839-416: The area. If a TGA decoder cannot interpret the information in the developer area, it will generally ignore it, since it is assumed to have been created by a different application. It is recommended that developers build logic into their applications to determine whether the data in the developer area is compatible with the application; one step towards this is to check the software ID in the file footer. If

7956-1163: The case. Sometimes function words are included to make a pronounceable acronym, such as CORE ( Congress of Racial Equality ). Sometimes the letters representing these words are written in lower case, such as in the cases of "TfL" (" Transport for London ") and LotR ( The Lord of the Rings ); this usually occurs when the acronym represents a multi-word proper noun. Numbers (both cardinal and ordinal ) in names are often represented by digits rather than initial letters, as in "4GL" (" fourth generation language ") or "G77" (" Group of 77 "). Large numbers may use metric prefixes , as with " Y2K " for "Year 2000". Exceptions using initials for numbers include " TLA " ("three-letter acronym/abbreviation") and "GoF" (" Gang of Four "). Abbreviations using numbers for other purposes include repetitions, such as " A2DP " ("Advanced Audio Distribution Profile"), " W3C " ("World Wide Web Consortium"), and T3 ( Trends, Tips & Tools for Everyday Living ); pronunciation, such as " B2B " ("business to business"); and numeronyms , such as "i18n" ("internationalization"; "18" represents

8073-413: The compact discs). In some instances, however, an apostrophe may increase clarity: for example, if the final letter of an abbreviation is "S", as in "SOS's" (although abbreviations ending with S can also take "-es", e.g. "SOSes"), or when pluralizing an abbreviation that has periods. A particularly rich source of options arises when the plural of an acronym would normally be indicated in a word other than

8190-564: The contrived acronym "P.R.E.T.T.Y.B.L.U.E.B.A.T.C.H." The use of Latin and Neo-Latin terms in vernaculars has been pan-European and pre-dates modern English. Some examples of acronyms in this class are: The earliest example of a word derived from an acronym listed by the OED is "abjud" (now " abjad "), formed from the original first four letters of the Arabic alphabet in the late eighteenth century. Some acrostics pre-date this, however, such as

8307-470: The date and time the image was created is catered for in the extension area. Color map type (field 2) has the value: Image type (field 3) is enumerated in the lower three bits, with the fourth bit as a flag for RLE. Some possible values are: Image type 1 and 9: Depending on the Pixel Depth value, image data representation is an 8, 15, or 16 bit index into a color map that defines the color of

8424-438: The dictionary entries and style guide recommendations regarding the term acronym through the twentieth century did not explicitly acknowledge or support the expansive sense. The Merriam–Webster's Dictionary of English Usage from 1994 is one of the earliest publications to advocate for the expansive sense, and all the major dictionary editions that include a sense of acronym equating it with initialism were first published in

8541-446: The endianness is the same for floating-point numbers as for integers, making the conversion straightforward regardless of data type. Small embedded systems using special floating-point formats may be another matter, however. Most instructions considered so far contain the size (lengths) of their operands within the operation code . Frequently available operand lengths are 1, 2, 4, 8, or 16 bytes. But there are also architectures where

8658-664: The exclusive sense for acronym and its earliest citation was from 1943. In early December 2010, Duke University researcher Stephen Goranson published a citation for acronym to the American Dialect Society e-mail discussion list which refers to PGN being pronounced "pee-gee-enn", antedating English language usage of the word to 1940. Linguist Ben Zimmer then mentioned this citation in his December 16, 2010 " On Language " column about acronyms in The New York Times Magazine . By 2011,

8775-460: The existing endianness to maintain backward compatibility . A big-endian system stores the most significant byte of a word at the smallest memory address and the least significant byte at the largest. A little-endian system, in contrast, stores the least-significant byte at the smallest address. Of the two, big-endian is thus closer to the way the digits of numbers are written left-to-right in English, comparing digits to bytes. Bi-endianness

8892-457: The field starts . The integer data that are directly supported by the computer hardware have a fixed width of a low power of 2, e.g. 8 bits ≙ 1 byte, 16 bits ≙ 2 bytes, 32 bits ≙ 4 bytes, 64 bits ≙ 8 bytes, 128 bits ≙ 16 bytes. The low-level access sequence to the bytes of such a field depends on the operation to be performed. The least-significant byte is accessed first for addition , subtraction and multiplication . The most-significant byte

9009-763: The final word if spelled out in full. A classic example is "Member of Parliament", which in plural is "Members of Parliament". It is possible then to abbreviate this as "M's P", which was fairly common in mid-twentieth-century Australian news writing (or similar ), and used by former Australian Prime Minister Ben Chifley . This usage is less common than forms with "s" at the end, such as "MPs", and may appear dated or pedantic. In common usage, therefore, "weapons of mass destruction" becomes "WMDs", "prisoners of war" becomes "POWs", and "runs batted in" becomes "RBIs". Abbreviations that come from single, rather than multiple, words – such as "TV" ("television") – are usually pluralized without apostrophes ("two TVs"); most writers feel that

9126-423: The first incarnations of the TGA file format. The file extensions ".vda" and ".icb" implied information about the board specific data contained. It was later determined by Alan Wlasuk (then head of EPICenter), Brad Pillow (EPICenter) and Steven Dompier (Island's president) that a more codified file format was needed. The file format was created and implemented by Brad Pillow (EPICenter) and Bryan Hunt (EPICenter) and

9243-464: The first letter of acronyms, reserving all-caps styling for initialisms, writing the pronounced acronyms "Nato" and "Aids" in mixed case, but the initialisms "USA" and "FBI" in all caps. For example, this is the style used in The Guardian , and BBC News typically edits to this style (though its official style guide, dating from 2003, still recommends all-caps ). The logic of this style is that

9360-446: The image data as packed RGB data. In contrast, BMP requires padding rows to 4-byte boundaries, while TIFF and PNG are metadata containers that do not place the image data or attributes at a fixed location within the file. 32-bit TGA images contain an alpha channel, or key signal, and are often used in character generator programs such as Avid Deko. All values are little-endian ; field and subfield numbers are per Version 2.0 of

9477-435: The king". In English, abbreviations have previously been marked by a wide variety of punctuation . Obsolete forms include using an overbar or colon to show the ellipsis of letters following the initial part. The forward slash is still common in many dialects for some fixed expressions—such as in w/ for "with" or A/C for " air conditioning "—while only infrequently being used to abbreviate new terms. The apostrophe

9594-500: The label "usage problem". However, many English language dictionaries, such as the Collins COBUILD Advanced Dictionary , Cambridge Advanced Learner's Dictionary , Macmillan Dictionary , Longman Dictionary of Contemporary English , New Oxford American Dictionary , Webster's New World Dictionary , and Lexico from Oxford University Press do not acknowledge such a sense. Most of

9711-836: The language to changing circumstances. In this view, the modern practice is just the "proper" English of the current generation of speakers, much like the earlier abbreviation of corporation names on ticker tape or newspapers. Exact pronunciation of "word acronyms" (those pronounced as words rather than sounded out as individual letters) often vary by speaker population. These may be regional, occupational, or generational differences, or simply personal preference. For instance, there have been decades of online debate about how to pronounce GIF ( / ɡ ɪ f / or / dʒ ɪ f / ) and BIOS ( / ˈ b aɪ oʊ s / , / ˈ b aɪ oʊ z / , or / ˈ b aɪ ɒ s / ). Similarly, some letter-by-letter initialisms may become word acronyms over time, especially in combining forms: IP for Internet Protocol

9828-406: The late 1990s (SPARC v9 compliant processors) allow data endianness to be chosen with each individual instruction that loads from or stores to memory. The ARM architecture supports two big-endian modes, called BE-8 and BE-32 . CPUs up to ARMv5 only support BE-32 or word-invariant mode. Here any naturally aligned 32-bit access works like in little-endian mode, but access to a byte or 16-bit word

9945-588: The length of an operand may be held in a separate field of the instruction or with the operand itself, e.g. by means of a word mark . Such an approach allows operand lengths up to 256 bytes or larger. The data types of such operands are character strings or BCD . Machines able to manipulate such data with one instruction (e.g. compare, add) include the IBM 1401 , 1410 , 1620 , System/360 , System/370 , ESA/390 , and z/Architecture , all of them of type big-endian. Numerous other orderings, generically called middle-endian or mixed-endian , are possible. The PDP-11

10062-497: The logic of networking devices and software. The word bi-endian , when said of hardware, denotes the capability of the machine to compute or pass data in either endian format. Many of these architectures can be switched via software to default to a specific endian format (usually done when the computer starts up); however, on some systems, the default endianness is selected by hardware on the motherboard and cannot be changed via software (e.g. Alpha, which runs only in big-endian mode on

10179-514: The middle of sentences for proper nouns; when following the AMA Manual of Style , this would instead be rendered as "the onset of congestive heart failure (CHF)". Endianness In computing , endianness is the order in which bytes within a word of digital data are transmitted over a data communication medium or addressed (by rising addresses) in computer memory , counting only byte significance compared to earliness. Endianness

10296-466: The more general "x" can be used to replace an unspecified number of letters. Examples include "Crxn" for "crystallization" and the series familiar to physicians for history , diagnosis , and treatment ("hx", "dx", "tx"). Terms relating to a command structure may also sometimes use this formatting, for example gold, silver, and bronze levels of command in UK policing being referred to as Gx, Sx, and Bx. There

10413-429: The newer v2.0 TGA specification. Initialism An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with the initial letter of each word in all caps with no punctuation . For some, an initialism or alphabetism , connotes this general meaning, and an acronym

10530-403: The number of bytes in the data. An attempt to read such a file using Fortran on a system of the other endianness results in a run-time error, because the count fields are incorrect. Unicode text can optionally start with a byte order mark (BOM) to signal the endianness of the file or stream. Its code point is U+FEFF. In UTF-32 for example, a big-endian file should start with 00 00 FE FF ;

10647-533: The only bit depths supported in practice were 8, 15, 16, 24, and 32, where the 16- and 32-bit formats used 1 and 8 bits respectively for the alpha channel. Color data can be color-mapped , or in direct color or truecolor format. Image data may be stored raw, or optionally, a lossless RLE compression similar to PackBits can be employed. This type of compression performs poorly for typical photographic images, but works acceptably well for simpler images, such as icons, cartoons and line drawings. The TGA file format

10764-424: The pixel. Image type 2 and 10: The image data is a direct representation of the pixel color. For a Pixel Depth of 15 and 16 bit, each pixel is stored with 5 bits per color. If the pixel depth is 16 bits, the topmost bit is reserved for transparency. For a pixel depth of 24 bits, each pixel is stored with 8 bits per color. A 32-bit pixel depth defines an additional 8-bit alpha channel. Image type 3 and 11: The image data

10881-729: The plural of 'pages', or mss. for manuscripts . The most common capitalization scheme seen with acronyms is all-uppercase ( all caps ). Small caps are sometimes used to make the run of capital letters seem less jarring to the reader. For example, the style of some American publications, including the Atlantic Monthly and USA Today , is to use small caps for acronyms longer than three letters; thus "U.S." and " FDR " in normal caps, but " nato " in small caps. The acronyms " AD " and " BC " are often smallcapped as well, as in: "From 4004 bc to ad 525 ". Where an acronym has linguistically taken on an identity as regular word,

10998-560: The point of view of the executing programs, but they require the motherboard to perform a 64-bit swap across all 8 byte lanes to ensure that the little-endian view of things will apply to I/O devices. In the absence of this unusual motherboard hardware, device driver software must write to different addresses to undo the incomplete transformation and also must perform a normal byte swap. Some CPUs, such as many PowerPC processors intended for embedded use and almost all SPARC processors, allow per-page choice of endianness. SPARC processors since

11115-483: The pronunciation is reflected graphically by the capitalization scheme. However, it conflicts with conventional English usage of first-letter upper-casing as a marker of proper names in many cases; e.g. AIDS stands for acquired immuno-deficiency syndrome which is not a proper name, while Aids is in the style of one. Some style manuals also base the letters' case on their number. The New York Times , for example, keeps "NATO" in all capitals (while several guides in

11232-685: The publication of the 3rd edition of the Oxford English Dictionary added the expansive sense to its entry for acronym and included the 1940 citation. As the Oxford English Dictionary structures the senses in order of chronological development, it now gives the "initialism" sense first. English language usage and style guides which have entries for acronym generally criticize the usage that refers to forms that are not pronounceable words. Fowler's Dictionary of Modern English Usage says that acronym "denotes abbreviations formed from initial letters of other words and pronounced as

11349-427: The same address as either 8-bit (value = 4A), 16-bit (004A), 24-bit (00004A), or 32-bit (0000004A), all of which retain the same numeric value. Although this little-endian property is rarely used directly by high-level programmers, it is occasionally employed by code optimizers as well as by assembly language programmers. While not allowed by C++, such type punning code is allowed as "implementation-defined" by

11466-444: The sequence the bytes are accessed by the computer hardware, more precisely: by the low-level algorithms contributing to the results of a computer instruction. Positional number systems (mostly base 2, or less often base 10) are the predominant way of representing and particularly of manipulating integer data by computers. In pure form this is valid for moderate sized non-negative integers, e.g. of C data type unsigned . In such

11583-406: The shell of a boiled egg from the big end or from the little end. By analogy, a CPU may read a digital word big end first, or little end first. Computers store information in various-sized groups of binary bits. Each group is assigned a number, called its address , that the computer uses to access that data. On most modern computers, the smallest data group with an address is eight bits long and

11700-470: The sides of railroad cars (e.g., "Richmond, Fredericksburg and Potomac Railroad" → "RF&P"); on the sides of barrels and crates; and on ticker tape and newspaper stock listings (e.g. American Telephone and Telegraph Company → AT&T). Some well-known commercial examples dating from the 1890s through 1920s include " Nabisco " ("National Biscuit Company"), " Esso " (from "S.O.", from " Standard Oil "), and " Sunoco " ("Sun Oil Company"). Another field for

11817-461: The significance increasing from right to left. In other words, it appears backwards when visualized, which can be counter-intuitive. This behavior arises, for example, in FourCC or similar techniques that involve packing characters into an integer, so that it becomes a sequence of specific characters in memory. For example, take the string "JOHN", stored in hexadecimal ASCII . On big-endian machines,

11934-411: The specification. Version 2 added the extension area and footer. The developer area exists to store application-specific information. Image ID length (field 1) 0–255 The number of bytes that the image ID field consists of. The image ID field can contain any information, but it is common for it to contain the date and time the image was created or a serial number. As of version 2.0 of the TGA spec,

12051-423: The telephone book. Almost all machines which can do this using a single instruction are big-endian or at least mixed-endian. Integer numbers written as text are always represented most significant digit first in memory, which is similar to big-endian, independently of text direction . When memory bytes are printed sequentially from left to right (e.g. in a hex dump ), little-endian representation of integers has

12168-476: The term acronym only for forms pronounced as a word, and using initialism or abbreviation for those that are not. Some sources acknowledge the usage, but vary in whether they criticize or forbid it, allow it without comment, or explicitly advocate it. Some mainstream English dictionaries from across the English-speaking world affirm a sense of acronym which does not require being pronounced as

12285-502: The terms as mutually exclusive. Other guides outright deny any legitimacy to the usage: Bryson's Dictionary of Troublesome Words says "Abbreviations that are not pronounced as words (IBM, ABC, NFL) are not acronyms; they are just abbreviations." Garner's Modern American Usage says "An acronym is made from the first letters or parts of a compound term. It's read or spoken as a single word, not letter by letter." The New York Times Manual of Style and Usage says "Unless pronounced as

12402-570: The twenty-first century. The trend among dictionary editors appears to be towards including a sense defining acronym as initialism : the Merriam-Webster's Collegiate Dictionary added such a sense in its 11th edition in 2003, and both the Oxford English Dictionary and The American Heritage Dictionary added such senses in their 2011 editions. The 1989 edition of the Oxford English Dictionary only included

12519-409: The two should be encoded as separate packets. In other words, Run-length Packets should not wrap from one line to another". Consequently TGA readers need to be able to handle RLE data packets that cross scan lines since this was part of the original specification. However, when saving (creating) TGA files it will be necessary to limit RLE data packets to scanline boundaries in order to be compliant with

12636-997: The value appears left-to-right, coinciding with the correct string order for reading the result ("J O H N"). But on a little-endian machine, one would see "N H O J". Middle-endian machines complicate this even further; for example, on the PDP-11 , the 32-bit value is stored as two 16-bit words "JO" "HN" in big-endian, with the characters in the 16-bit words being stored in little-endian, resulting in "O J N H". Byte-swapping consists of rearranging bytes to change endianness. Many compilers provide built-ins that are likely to be compiled into native processor instructions ( bswap / movbe ), such as __builtin_bswap32 . Software interfaces for swapping include: Some CPU instruction sets provide native support for endian byte swapping, such as bswap ( x86 — 486 and later, i960 — i960Jx and later ), and rev ( ARMv6 and later). Some compilers have built-in facilities for byte swapping. For example,

12753-536: The whole range of linguistic registers is relatively new in most languages, becoming increasingly evident since the mid-twentieth century. As literacy spread and technology produced a constant stream of new and complex terms, abbreviations became increasingly convenient. The Oxford English Dictionary ( OED ) records the first printed use of the word initialism as occurring in 1899, but it did not come into general use until 1965, well after acronym had become common. In English, acronyms pronounced as words may be

12870-425: The word " an achro nym ", which is a type of misnomer. Words derived from an acronym by affixing are typically expressed in mixed case, so the root acronym is clear. For example, "pre-WWII politics", "post-NATO world", " DNase ". In some cases a derived acronym may also be expressed in mixed case. For example, " messenger RNA " and " transfer RNA " become "mRNA" and "tRNA". Some publications choose to capitalize only

12987-723: Was authored by Truevision Inc.'s Shawn Steiner with direction from Kevin Friedly and David Spoelstra in 1989. At the time of its launching, it represented the state of the art in digital image processing. Even today, though its maximum color depth is not well suited for high-end pre-press, intensive image processing systems, TGA is still used extensively throughout the animation and video industry because its primary intended outputs are standard TV screens, not color printed pages. Uncompressed 24-bit TGA images are relatively simple compared to several other prominent 24-bit storage formats: A 24-bit TGA contains only an 18-byte header followed by

13104-453: Was developed in response to this need for a less board specific file format. A very simple extension was made to what was already in use, and contained information on width, height, pixel depth, an associated color map and image origin. A label field (up to 255 characters) was also included in the initial spec, but was rarely used. At the time, another technically superior file format called TIFF also appeared, but its use for true color images

13221-511: Was done with a full space between every full word (e.g. A. D. , i. e. , and e. g. for " Anno Domini ", " id est ", and " exempli gratia "). This even included punctuation after both Roman and Arabic numerals to indicate their use in place of the full names of each number (e.g. LII. or 52. in place of "fifty-two" and "1/4." or "1./4." to indicate "one-fourth"). Both conventions have fallen out of common use in all dialects of English, except in places where an Arabic decimal includes

13338-449: Was little to no naming , conscious attention, or systematic analysis until relatively recent times. Like retronymy, it became much more common in the twentieth century than it had formerly been. Ancient examples of acronymy (before the term "acronym" was invented) include the following: During the mid- to late nineteenth century, acronyms became a trend among American and European businessmen: abbreviating corporation names, such as on

13455-496: Was originally defined and specified by AT&T EPICenter with feedback from Island Graphics Inc in 1984. AT&T EPICenter was an internal spin-off of AT&T created to market new technologies AT&T had developed for color frame buffers . What later became Truevision was the result of a leveraged employee buyout from AT&T in 1987. EPICenter's first two cards, the VDA (video display adapter) and ICB (image capture board), used

13572-513: Was unable to deliver the 8008 in time, Datapoint used a medium-scale integration equivalent, but the little-endianness was retained in most Intel designs, including the MCS-48 and the 8086 and its x86 successors, including IA-32 and x86-64 processors. The MOS Technology 6502 family (including Western Design Center 65802 and 65C816 ), the Zilog Z80 (including Z180 and eZ80 ),

13689-847: Was very limited as the implementation and sharing of files between applications supporting the TIFF specification was rather difficult and involved. The TGA file format's simpler nature and portability between platforms is the main reason for its widespread adoption and its continued success in a wide variety of applications worldwide to this day. Initially the TGA file format was used in the ICB-PAINT and TARGA-PAINT programs (what later became known as TIPS) and for several projects in online real estate browsing and still-frame video teleconferencing. The current version (2.0) includes several enhancements such as "postage stamps" (better known as thumbnails ), an alpha channel , gamma value, and textual metadata , and

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