ISO 31-0

ISO 31-0 is the introductory part of international standard ISO 31 on quantities and units. It provides guidelines for using physical quantities, quantity and unit symbols, and coherent unit systems, especially the SI. It is intended for use in all fields of science and technology and is augmented by more specialized conventions defined in other parts of the ISO 31 standard. ISO 31-0 was withdrawn on 17 November 2009. It is superseded by ISO 80000-1. Other parts of ISO 31 have also been withdrawn and replaced by parts of ISO 80000.

Scope

ISO 31 covers only physical quantities used for the quantitative description of physical phenomena. It does not cover conventional scales (e.g., Beaufort scale, Richter scale, colour intensity scales), results of conventional tests, currencies, or information content. The presentation here is only a brief summary of some of the detailed guidelines and examples given in the standard.

Quantities and units

Physical quantities can be grouped into mutually comparable categories. For example, length, width, diameter and wavelength are all in the same category, that is they are all quantities of the same kind. One particular example of such a quantity can be chosen as a reference quantity, called the unit, and then all other quantities in the same category can be expressed in terms of this unit, multiplied by a number called the numerical value. For example, if we write

the wavelength is λ = 6.982 × 10−7 m

then "λ" is the symbol for the physical quantity (wavelength), "m" is the symbol for the unit (metre), and "6.982 × 10−7" is the numerical value of the wavelength in metres.

More generally, we can write

A = {A} ⋅ [A]

where A is the symbol for the quantity, {A} symbolizes the numerical value of A, and [A] represents the corresponding unit in which A is expressed here. Both the numerical value and the unit symbol are factors, and their product is the quantity. A quantity itself has no inherent particular numerical value or unit; as with any product, there are many different combinations of numerical value and unit that lead to the same quantity (e.g., A = 300 ⋅ m = 0.3 ⋅ km = ...). This ambiguity makes the {A} and [A] notations useless, unless they are used together.

The value of a quantity is independent of the unit chosen to represent it. It must be distinguished from the numerical value of the quantity that occurs when the quantity is expressed in a particular unit. The above curly-bracket notation could be extended with a unit-symbol index to clarify this dependency, as in {λ} = 6.982 × 10−7 or equivalently {λ} = 698.2. In practice, where it is necessary to refer to the numerical value of a quantity expressed in a particular unit, it is notationally more convenient to simply divide the quantity through that unit, as in

λ/m = 6.982 × 10−7

or equivalently

λ/nm = 698.2.

This is a particularly useful and widely used notation for labelling the axes of graphs or for the headings of table columns, where repeating the unit after each numerical value can be typographically inconvenient.

Typographic conventionsSymbols for quantities
  • Quantities are generally represented by a symbol formed from single letters of the Latin or Greek alphabet.
  • Symbols for quantities are set in italic type, independent of the type used in the rest of the text.
  • If in a text different quantities use the same letter symbol, they can be distinguished via subscripts.
  • A subscript is only set in italic type if it consists of a symbol for a quantity or a variable. Other subscripts are set in upright (roman) type. For example, write V for a "nominal volume" (where "n" is just an abbreviation for the word "nominal"), but write V if n is a running index number.
Names and symbols for units
  • If an internationally standardized symbol exists for a unit, then only that symbol should be used. See the SI articles for the list of standard symbols defined by the International System of Units. Note that the distinction between uppercase and lowercase letters is significant for SI unit symbols. For example, "k" is the prefix kilo and "K" stands for the unit kelvin. The symbols of all SI units named after a person or a place start with an uppercase letter, as do the symbols of all prefixes from mega on upwards. All other symbols are lowercase; the only exception is litre, where both l and L are allowed. However, it is stated that the CIPM will examine whether one of the two may be suppressed.
  • Symbols for units should be printed in an upright (roman) typeface.
Numbers

See Sect. 3.3 of the Standard text.

  • Numbers should be printed in upright (roman) type.
  • ISO 31-0 (after Amendment 2) specifies that "the decimal sign is either the comma on the line or the point on the line". This follows resolution 10[1] of the 22nd CGPM, 2003.[2]
For example, one divided by two (one half) may be written as 0.5 or 0,5.
  • Numbers consisting of long sequences of digits can be made more readable by separating them into groups, preferably groups of three, separated by a small space. For this reason, ISO 31-0 specifies that such groups of digits should never be separated by a comma or point, as these are reserved for use as the decimal sign.
For example, one million (1000000) may be written as 1 000 000.
  • For numbers whose magnitude is less than 1, the decimal sign should be preceded by a zero.
  • The multiplication sign is either a cross or a half-height dot, though the latter should not be used when the dot is the decimal separator.
Expressions
  • Unit symbols follow the numerical value in the expression of a quantity.
  • Numerical value and unit symbol are separated by a space. This rule also applies to the symbol "°C" for degrees Celsius, as in "25 °C". The only exception are the symbols for the units of plane angle degree, minute and second, which follow the numerical value without a space in between (for example "30°").
  • Where quantities are added or subtracted, parenthesis can be used to distribute a unit symbol over several numerical values, as in
T = 25 °C − 3 °C = (25 − 3) °C
P = 100 kW ± 5 kW = (100 ± 5) kW
(but not: 100 ± 5 kW)
d = 12 × (1 ± 10−4) m
  • Products can be written as ab, a b, a⋅b, or a×b. The sign for multiplying numbers is a cross (×) or a half-height dot (⋅). The cross should be used adjacent to numbers if a dot on the line is used as the decimal separator, to avoid confusion between a decimal dot and a multiplication dot.
  • Division can be written as a b {\displaystyle {\frac {a}{b}}} , a/b, or by writing the product of a and b−1, for example a⋅b−1. Numerator or denominator can themselves be products or quotients, but in this case, a solidus (/) should not be followed by a multiplication sign or division sign on the same line, unless parentheses are used to avoid ambiguity.
Mathematical signs and symbols

A comprehensive list of internationally standardized mathematical symbols and notations can be found in ISO 31-11.

See also References
  1. "Resolution 10", 22nd General Conference on Weights and Measures, BIPM.
  2. Brief reference to the history, NIST.
Bibliography
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International Securities Identification Number

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International Securities Identification Number

An International Securities Identification Number (ISIN) uniquely identifies a security. Its structure is defined in ISO 6166. The ISIN code is a 12-character alphanumeric code that serves for uniform identification of a security through normalization of the assigned National Number, where one exists, at trading and settlement. History ISINs were first used in 1981, but didn't reach wide acceptance until 1989, when the G30 countries recommended adoption.[1] The ISIN was endorsed a year later by ISO with the ISO 6166 standard. Initially information was distributed via CD-ROMs and this was later replaced by distribution over the internet. In 2004 the European Union mandated the use of instrument identifiers in some of its regulatory reporting, which included ISIN as one of the valid identifiers.[2] Description ISO 6166 (or ISO6166:2013 as of the 2013 revision) defines the structure of an International Securities Identification Number (ISIN). An ISIN uniquely identifies a fungible security. Securities with ...more...

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ISO/IEC 8859-16

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ISO/IEC 8859-16

ISO/IEC [1]8859-16:2001, Information technology — 8-bit single-byte coded graphic character sets — Part 16: Latin alphabet No. 10, is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 2001. It is informally referred to as Latin-10 or South-Eastern European. It was designed to cover Albanian, Croatian, Hungarian, Polish, Romanian, Serbian and Slovenian, but also French, German, Italian and Irish Gaelic (new orthography). ISO-8859-16 is the IANA preferred charset name for this standard when supplemented with the C0 and C1 control codes from ISO/IEC 6429. Microsoft has assigned code page 28606 a.k.a. Windows-28606 to ISO-8859-16.[2] Codepage layout Legend:   Alphabetic   Control character   Numeric digit   Punctuation   Extended punctuation   Graphic character   International   Undefined Differences from ISO/IEC 8859-1 have a black border. ISO/IEC 8859-16 _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F   0_     1_   ...more...

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ISO 5426

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ISO 5426

ISO 5426 is character set developed by ISO. It was first published in 1983. Character set ISO 5426 _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F   0_   NUL00000 SOH00011 STX00022 ETX00033 EOT00044 ENQ00055 ACK00066 BEL00077 BS00088 HT00099 LF000A10 VT000B11 FF000C12 CR000D13 SO000E14 SI000F15   1_   DLE001016 DC1001117 DC2001218 DC3001319 DC4001420 NAK001521 SYN001622 ETB001723 CAN001824 EM001925 SUB001A26 ESC001B27 FS001C28 GS001D29 RS001E30 US001F31   2_   SP002032 ¡00A133 „201E34 £00A335 $002436 ¥00A537 †202038 §00A739 ʹ02BE40 ‘201841 “201C42 «00AB43 ♭266D44 ©00A945 ℗211746 ®00AE47   3_   ʿ02BF48 ʾ02BE49 ‚201A50 51 52 53 ‡202154 ·00B755 ʺ02BA56 ’201957 ”201D58 »00BB59 ♯266F60 ′02B961 ʺ02BA62 ¿00BF63   4_   ̉030964 ̀030065 ́030166 ̂030267 ̃030368 ̄030469 ̆030670 ̇030771 ̈030872 ̈030873 ̊030A74 ̕031575 ̒031276 ̋030B77 ̛031B78 ̌030C79   5_   ̧032780 ̨032881 ̡032182 ̢032283 ̥032584 ̮032E85 ̣032386 ̤032487 ̲033288 ̳033389 ̩032990 ̭032D91 92 ︠FE2093 ︡FE2194 ︣FE2395   6_   96 Æ00C697 Đ00D098 99 100 101 IJ013 ...more...

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ISO base media file format

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ISO base media file format

ISO base media file format (ISO/IEC 14496-12 – MPEG-4 Part 12) defines a general structure for time-based multimedia files such as video and audio.[1][2] The identical text is published as ISO/IEC 15444-12 (JPEG 2000, Part 12).[3] It is designed as a flexible, extensible format that facilitates interchange, management, editing and presentation of the media. The presentation may be local, or via a network or other stream delivery mechanism. The file format is designed to be independent of any particular network protocol while enabling support for them in general.[2] It is used as the basis for other media file formats (e.g. container formats MP4 and 3GP). HistoryEdit ISO base media file format is directly based on Apple’s QuickTime container format.[4][5][6][7][8] It was developed by MPEG (ISO/IEC JTC1/SC29/WG11). The first MP4 file format specification was created on the basis of the QuickTime format specification published in 2001.[9] The MP4 file format known as "version 1" was published in 2001 as ISO/IE ...more...

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3GP and 3G2

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3GP and 3G2

3GP (3GPP file format) is a multimedia container format defined by the Third Generation Partnership Project (3GPP) for 3G UMTS multimedia services. It is used on 3G mobile phones but can also be played on some 2G and 4G phones. 3G2 (3GPP2 file format) is a multimedia container format defined by the 3GPP2 for 3G CDMA2000 multimedia services. It is very similar to the 3GP file format but consumes less space & bandwidth also has some extensions and limitations in comparison to 3GP. Specifications 3GP is defined in the ETSI 3GPP technical specification.[1] 3GP is a required file format for video and associated speech/audio media types and timed text in ETSI 3GPP technical specifications for IP Multimedia Subsystem (IMS), Multimedia Messaging Service (MMS), Multimedia Broadcast/Multicast Service (MBMS) and Transparent end-to-end Packet-switched Streaming Service (PSS).[2][3][4][5] 3G2 is defined in the 3GPP2 technical specification.[6] Technical details Relations between ISO Base Media File Format, MP ...more...

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OpenDocument

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OpenDocument

The Open Document Format for Office Applications (ODF), also known as OpenDocument, is a ZIP-compressed[6] XML-based file format for spreadsheets, charts, presentations and word processing documents. It was developed with the aim of providing an open, XML-based file format specification for office applications.[7] The standard was developed by a technical committee in the Organization for the Advancement of Structured Information Standards (OASIS) consortium.[8] It was based on the Sun Microsystems specification for OpenOffice.org XML, the default format for OpenOffice.org, which had been specifically intended "to provide an open standard for office documents."[9] In addition to being an OASIS standard, it was published as an ISO/IEC international standard ISO/IEC 26300 – Open Document Format for Office Applications (OpenDocument).[2][3][4][5][10][11] Specifications The most common filename extensions used for OpenDocument documents are:[12][13] .odt and .fodt for word processing (text) documents .ods ...more...

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MPEG-1

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MPEG-1

MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively)[1] without excessive quality loss, making video CDs, digital cable/satellite TV and digital audio broadcasting (DAB) possible.[2][3] Today, MPEG-1 has become the most widely compatible lossy audio/video format in the world, and is used in a large number of products and technologies. Perhaps the best-known part of the MPEG-1 standard is the MP3 audio format it introduced. The MPEG-1 standard is published as ISO/IEC 11172 – Information technology—Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s. The standard consists of the following five Parts:[4][5][6][7][8] Systems (storage and synchronization of video, audio, and other data together) Video (compressed video content) Audio (compressed audio content) Conformance testing (testing the correctness of implementa ...more...

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Near-field communication

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Near-field communication

Near-field communication (NFC) is a set of communication protocols that enable two electronic devices, one of which is usually a portable device such as a smartphone, to establish communication by bringing them within 4 cm (1.6 in) of each other.[1] NFC devices are used in contactless payment systems, similar to those used in credit cards and electronic ticket smartcards and allow mobile payment to replace/supplement these systems. This is sometimes referred to as NFC/CTLS (Contactless) or CTLS NFC. NFC is used for social networking, for sharing contacts, photos, videos or files.[2] NFC-enabled devices can act as electronic identity documents and keycards.[3] NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections.[3] The Secure Element chip. This is an NFC chip that contains data such as the SEID (Secure Element Identifier) for secure transactions. This chip is commonly found in smartphones and other NFC enabled devices Overview Similar idea ...more...

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ISO 2033

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ISO 2033

ISO 2033 is character set developed by ISO to used for OCR. Character set ISO 2033[1] _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _A _B _C _D _E _F   0_   NUL00000 SOH00011 STX00022 ETX00033 EOT00044 ENQ00055 ACK00066 BEL00077 BS00088 HT00099 LF000A10 VT000B11 FF000C12 CR000D13 SO000E14 SI000F15   1_   DLE001016 DC1001117 DC2001218 DC3001319 DC4001420 NAK001521 SYN001622 ETB001723 CAN001824 EM001925 SUB001A26 ESC001B27 FS001C28 GS001D29 RS001E30 US001F31   2_   SP002032 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47   3_   0003048 1003149 2003250 3003351 4003452 5003553 6003654 7003755 8003856 9003957 ⑆244658 ⑇244759 ⑈244860 ⑉244961 62 63   4_   64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79   5_   80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95   6_   96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111   7_   112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 DEL007F127 _0 _1 _2 _3 _4 _5 ...more...

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Brinell scale

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Brinell scale

Force diagram The Brinell scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science. Proposed by Swedish engineer Johan August Brinell in 1900, it was the first widely used and standardised hardness test in engineering and metallurgy. The large size of indentation and possible damage to test-piece limits its usefulness. However it also had the useful feature that the hardness value divided by two gave the approximate UTS in ksi for steels. This feature contributed to its early adoption over competing hardness tests. The typical test uses a 10 millimetres (0.39 in) diameter steel ball as an indenter with a 3,000 kgf (29.42 kN; 6,614 lbf) force. For softer materials, a smaller force is used; for harder materials, a tungsten carbide ball is substituted for the steel ball. The indentation is measured and hardness calculated as: BHN = 2 P π D ( D − ...more...

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Parts-per notation

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Parts-per notation

Fluorescein aqueous solutions, diluted from 1–10,000 parts-per-million In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are ppm (parts-per-million, 10−6), ppb (parts-per-billion, 10−9), ppt (parts-per-trillion, 10−12) and ppq (parts-per-quadrillion, 10−15). This notation is not part of the SI system and its meaning is ambiguous. Overview Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The unit “1 ppm” can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume that the density of water is 1.00 g/mL. Therefore, it ...more...

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Office Open XML

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Office Open XML

Office Open XML (also informally known as OOXML or Microsoft Open XML (MOX)[3]) is a zipped, XML-based file format developed by Microsoft[4] for representing spreadsheets, charts, presentations and word processing documents. The format was initially standardized by Ecma (as ECMA-376), and by the ISO and IEC (as ISO/IEC 29500) in later versions. Microsoft Office 2010 provides read support for ECMA-376, read/write support for ISO/IEC 29500 Transitional, and read support for ISO/IEC 29500 Strict.[5] Microsoft Office 2013 and Microsoft Office 2016 additionally support both reading and writing of ISO/IEC 29500 Strict.[6] Microsoft has not yet implemented the non-transitional, or original standard, as the default file format after more than a decade.[7] Background In 2000, Microsoft released an initial version of an XML-based format for Microsoft Excel, which was incorporated in Office XP. In 2002, a new file format for Microsoft Word followed.[8] The Excel and Word formats—known as the Microsoft Office XML forma ...more...

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Intermodal container

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Intermodal container

A 40-foot long (12.19 m) shipping container. Each of the eight corners has an essential twistlock fitting for hoisting, stacking, and securing In 2012 there were over 20 million intermodal containers in the world. Extra long 53 ft (16.15 m) × 9 ft 6 in (2.9 m) "High-Cube" container with an internal height of 110 in (2,794 mm) Freight train carrying containers through West Kingman Canyon, Arizona Making containers stackable made loading and transport on large ships feasible and efficient An intermodal container is a large standardized shipping container, designed and built for intermodal freight transport, meaning these containers can be used across different modes of transport – from ship to rail to truck – without unloading and reloading their cargo.[1] Intermodal containers are primarily used to store and transport materials and products efficiently and securely in the global containerized intermodal freight transport system, but smaller numbers are in regional use as well. These c ...more...

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ISO 15924

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ISO 15924

ISO 15924, Codes for the representation of names of scripts, defines two sets of codes for a number of writing systems (scripts). Each script is given both a four-letter code and a numeric one.[1] Script is defined as "set of graphic characters used for the written form of one or more languages".[1] Where possible the codes are derived from ISO 639-2 where the name of a script and the name of a language using the script are identical (example: Gujarātī ISO 639 guj, ISO 15924 Gujr). Preference is given to the 639-2 Bibliographical codes, which is different from the otherwise often preferred use of the Terminological codes.[1] 4-letter ISO 15924 codes are incorporated into the Language Subtag Registry for IETF language tags and so can be used in file formats that make use of such language tags. For example, they can be used in HTML and XML to help Web browsers determine which typeface to use for foreign text. This way one could differentiate, for example, between Serbian written in the Cyrillic (sr-Cyrl) or L ...more...

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Dimension (metadata)

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Dimension (metadata)

In metadata, dimension is a set of equivalent units of measure, where equivalence between two units of measure is determined by the existence of a quantity preserving one-to-one correspondence between values measured in one unit of measure and values measured in the other unit of measure, independent of context, and where characterizing operations are the same. The equivalence defined here forms an equivalence relation on the set of all units of measure. Each equivalence class corresponds to a dimensionality. The units of measure "temperature in degrees Fahrenheit" and "temperature in degrees Celsius" have the same dimensionality, because given a value measured in degrees Fahrenheit there is a value measured in degrees Celsius with the same quantity, and vice versa. Quantity preserving one-to-one correspondences are the well-known equations Cº = (5/9)*(Fº − 32) and Fº = (9/5)*(Cº) + 32. Units of measure are not limited to physical categories. Examples of physical categories are: linear measure, area, volume ...more...

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Kilowatt hour

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Kilowatt hour

The kilowatt hour (symbol kWh, kW⋅h or kW h) is a unit of energy equal to 3.6 megajoules. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt hours is equal to the power in kilowatts multiplied by the time in hours. The kilowatt hour is commonly used as a billing unit for energy delivered to consumers by electric utilities. Definition The kilowatt hour (symbolized kW⋅h as per SI) is a composite unit of energy equivalent to one kilowatt (1 kW) of power sustained for one hour. One watt is equal to 1 J/s. One kilowatt hour is 3.6 megajoules,[1][2] which is the amount of energy converted if work is done at an average rate of one thousand watts for one hour. The base unit of energy within the International System of Units (SI) is the joule. The hour is a unit of time "outside the SI", making the kilowatt hour a non-SI unit of energy. The kilowatt hour is not listed among the non-SI units accepted by the BIPM for use with the SI, although the h ...more...

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ISO 10303

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ISO 10303

ISO 10303 is an ISO standard for the computer-interpretable representation and exchange of product manufacturing information. Its official title is: Automation systems and integration — Product data representation and exchange. It is known informally as "STEP", which stands for "Standard for the Exchange of Product model data". ISO 10303 can represent 3D objects in Computer-aided design (CAD) and related information. Overview The international standard's objective is to provide a mechanism that is capable of describing product data throughout the life cycle of a product, independent from any particular system. The nature of this description makes it suitable not only for neutral file exchange, but also as a basis for implementing and sharing product databases and archiving.[1] Typically STEP can be used to exchange data between CAD, computer-aided manufacturing, computer-aided engineering, product data management/enterprise data modeling and other CAx systems. STEP addresses product data from mechanical and ...more...

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Nominal Pipe Size

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Nominal Pipe Size

Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures.[1] "Nominal" refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number (for example – 2-inch nominal steel pipe" consists of many varieties of steel pipe with the only criterion being a 2.375-inch (60.3 mm) outside diameter). Specific pipe is identified by pipe diameter and another non-dimensional number for wall thickness referred to as the Schedule (Sched. or Sch., for example – "2-inch diameter pipe, Schedule 40"). NPS is often incorrectly called National Pipe Size, due to confusion with the American standard for pipe threads, "national pipe straight", which also abbreviates as "NPS". The European and international designation equivalent to NPS is DN (diamètre nominal/nominal diameter/Durchmesser nach Norm), in which sizes are measured in millimetres, see ISO 6708.[2] The term NB (nominal bore) is also frequently used interchangeably w ...more...

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Grain size

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Grain size

Wentworth grain size chart from United States Geological Survey Open-File Report 2006-1195 Beach cobbles at Nash Point, South Wales. Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which refers to the size of a single crystal inside a particle or grain. A single grain can be composed of several crystals. Granular material can range from very small colloidal particles, through clay, silt, sand, gravel, and cobbles, to boulders. Krumbein phi scale Size ranges define limits of classes that are given names in the Wentworth scale (or Udden–Wentworth scale) used in the United States. The Krumbein phi (φ) scale, a modification of the Wentworth scale created by W. C. Krumbein[1] in 1937, is a logarithmic scale computed by the equation ϕ = − log 2 ⁡ D / D 0 , {\displaystyle \phi =-\log _{2}{D/D_{0}},} where ...more...

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Pedology

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Character encoding

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Character encoding

Character encoding is used to represent a repertoire of characters by some kind of encoding system.[1] Depending on the abstraction level and context, corresponding code points and the resulting code space may be regarded as bit patterns, octets, natural numbers, electrical pulses, etc. A character encoding is used in computation, data storage, and transmission of textual data. "Character set", "character map", "codeset" and "code page" are related, but not identical, terms. Early character codes associated with the optical or electrical telegraph could only represent a subset of the characters used in written languages, sometimes restricted to upper case letters, numerals and some punctuation only. The low cost of digital representation of data in modern computer systems allows more elaborate character codes (such as Unicode) which represent most of the characters used in many written languages. Character encoding using internationally accepted standards permits worldwide interchange of text in electronic f ...more...

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Slavic languages

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Slavic languages

The Slavic languages (also called Slavonic languages) are the Indo-European languages spoken by the Slavic peoples. They are thought to descend from a proto-language called Proto-Slavic spoken during the Early Middle Ages, which in turn is thought to have descended from the earlier Proto-Balto-Slavic language, linking the Slavic languages to the Baltic languages in a Balto-Slavic group within the Indo-European family. The Slavic languages are divided intro three subgroups: East, West, and South, which together constitute more than twenty languages. Of these, ten have at least one million speakers and official status as the national languages of the countries in which they are predominantly spoken: Russian, Belarusian and Ukrainian (of the East group), Polish, Czech and Slovak (of the West group) and Slovene, Serbo-Croatian, Macedonian and Bulgarian (of the South group). The current geographic distribution of natively spoken Slavic languages covers Eastern Europe, the Balkans, Central Europe and all of the t ...more...

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ISO 13849

topic

ISO 13849

ISO 13849 is a safety standard which deals with safety-related design principles of employed control systems to establish different safety Performance Levels (PL).[1] It replaced EN 954-1 in December 2011.[2] Part 1 defines the general principles for design. Part 2 describes the validation. References "Safety of machinery -- Safety-related parts of control systems -- Part 1: General principles for design". ISO. Retrieved 31 October 2013. "Safety and risk minimization in the operator control of plant machinery". Plant Engineering. October 21, 2013. Retrieved 31 October 2013. ...more...

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Standards in the Petroleum Industry

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Guobiao standards

topic

Guobiao standards

GB standards are the Chinese national standards issued by the Standardization Administration of China (SAC), the Chinese National Committee of the ISO and IEC. GB stands for Guobiao (simplified Chinese: 国标; traditional Chinese: 國標; pinyin: Guóbiāo), Chinese for national standard. Mandatory standards are prefixed "GB". Recommended standards are prefixed "GB/T" (T from Chinese language 推荐 tuījiàn, "recommended"). A standard number follows "GB" or "GB/T". GB standards are the basis for the product testing which products must undergo during the China Compulsory Certificate (CCC) certification. If there is no corresponding GB Standard, CCC is not required. List A non-exhaustive list of National Standards of the People's Republic of China is listed as follows, accompanied with similar international standards of ISO, marked as identical (IDT), equivalent (EQV), or non-equivalent (NEQ). Mandatory standards Number Equivalent to Title GB 2099.1‐2008 AC power mains plugs and sockets GB 1002‐2008 AC power m ...more...

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XML

topic

XML

In computing, Extensible Markup Language (XML) is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. The W3C's XML 1.0 Specification[2] and several other related specifications[3]—all of them free open standards—define XML.[4] The design goals of XML emphasize simplicity, generality, and usability across the Internet.[5] It is a textual data format with strong support via Unicode for different human languages. Although the design of XML focuses on documents, the language is widely used for the representation of arbitrary data structures[6] such as those used in web services. Several schema systems exist to aid in the definition of XML-based languages, while programmers have developed many application programming interfaces (APIs) to aid the processing of XML data. Applications of XML The essence of why extensible markup languages are necessary is explained at Markup language (for example, see Markup language § XML) and at Stand ...more...

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iz_kvizova

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IEC 60027

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IEC 60027

IEC 60027 (formerly IEC 27) is a technical international standard for letter symbols published by the International Electrotechnical Commission, comprising the following parts: IEC 60027-1: General IEC 60027-2: Telecommunications and electronics IEC 60027-3: Logarithmic and related quantities, and their units IEC 60027-4: Symbols for quantities to be used for rotating electrical machines IEC 60027-6: Control technology IEC 60027-7: Physiological quantities and units A closely related international standard on quantities and units is ISO 31. The ISO 31 and IEC 60027 Standards are being revised by the two standardization organizations in collaboration. The revised harmonized standard is known as ISO/IEC 80000, Quantities and units. It supersedes both ISO 31 and part of IEC 60027. IEC 60027-2 IEC 60027-2 Amendment 2, as published in January 1999, was the first international standard defining the binary prefixes, as proposed by International Electrotechnical Commission (IEC) since 1996 (kibi- (Ki), mebi ...more...

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Scientific notation

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Scientific notation

Scientific notation (also referred to as scientific form or standard index form, or standard form in the UK) is a way of expressing numbers that are too big or too small to be conveniently written in decimal form. It is commonly used by scientists, mathematicians and engineers, in part because it can simplify certain arithmetic operations. On scientific calculators it is usually known as "SCI" display mode. Decimal notation Scientific notation 2 2×100 300 3×102 4,321.768 4.321768×103 −53,000 −5.3×104 6,720,000,000 6.72×109 0.2 2×10−1 0.000 000 007 51 7.51×10−9 In scientific notation all numbers are written in the form m × 10n (m times ten raised to the power of n), where the exponent n is an integer, and the coefficient m is any real number, called the significand or mantissa.[1] However, the term "mantissa" may cause confusion because it is the name of the fractional part of the common logarithm. If the number is negative then a minus sign precedes m (as in ordinary decimal notation). ...more...

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Comparison of video container formats

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Comparison of video container formats

This table compares features of container formats (video file formats). To see which multimedia players support which container format, look at comparison of media players. Information Name and file extension Proprietor / developer License Variable bit rate audio Variable frame rate Chapters Captions / subtitles Video coding formats Audio coding formats Metadata / tags Menus[1] Streaming Attachment support[2] 3D, codecs 3D, container Hardware players 3GP 3GPP ? Yes Yes ? 3GPP Timed Text H.263, MPEG-4 Part 2 and H.264/MPEG-4 AVC AMR-NB, AMR-WB, AMR-WB+, AAC, HE-AAC and HE-AAC v2 ? No Yes[3] ? ? ? ? 3G2 3GPP2 ? Yes Yes ? 3GPP Timed Text H.263, MPEG-4 Part 2 and H.264/MPEG-4 AVC AMR-NB, AMR-WB, AAC, HE-AAC, EVRC, EVRC-B, EVRC-WB, 13K (QCELP), SMV or VMR-WB ? No Yes ? ? ? ? Advanced Systems Format (.asf, .wma, .wmv) Microsoft Proprietary, patent encumbered Yes Yes Yes Yes Almost anything through VFW or DMO; H.264/AVC is problematic Almost anything through ACM or DMO; Vorbis is problematic ...more...

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Web Content Accessibility Guidelines

topic

Web Content Accessibility Guidelines

The Web Content Accessibility Guidelines (WCAG) are part of a series of web accessibility guidelines published by the Web Accessibility Initiative (WAI) of the World Wide Web Consortium (W3C), the main international standards organization for the Internet. They are a set of guidelines that specify how to make content accessible, primarily for people with disabilities—but also for all user agents, including highly limited devices, such as mobile phones. The current version, WCAG 2.0, was published in December 2008 and became an ISO standard, ISO/IEC 40500:2012 in October 2012. WCAG 2.1 is a "Proposed Recommendation" as at April 2018.[1] Earlier guidelines The first web accessibility guideline was compiled by Gregg Vanderheiden and released in January 1995, just after the 1994 Second International Conference on the World-Wide Web (WWW II) in Chicago (where Tim Berners-Lee first mentioned disability access in a keynote speech after seeing a pre-conference workshop on accessibility led by Mike Paciello).[2] Ove ...more...

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Prolog

topic

Prolog

Prolog is a general-purpose logic programming language associated with artificial intelligence and computational linguistics.[1][2][3] Prolog has its roots in first-order logic, a formal logic, and unlike many other programming languages, Prolog is intended primarily as a declarative programming language: the program logic is expressed in terms of relations, represented as facts and rules. A computation is initiated by running a query over these relations.[4] The language was first conceived by a group around Alain Colmerauer in Marseille, France, in the early 1970s and the first Prolog system was developed in 1972 by Colmerauer with Philippe Roussel.[5][6] Prolog was one of the first logic programming languages,[7] and remains the most popular among such languages today, with several free and commercial implementations available. The language has been used for theorem proving,[8] expert systems,[9] term rewriting,[10] type inference,[11] and automated planning,[12] as well as its original intended field o ...more...

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Isetta

topic

Isetta

The Isetta is an Italian-designed microcar built under license in a number of different countries, including Argentina,[1] Spain,[2] Belgium,[3] France,[4] Brazil,[5] Germany,[6] and the United Kingdom.[7] Because of its egg shape and bubble-like windows, it became known as a bubble car, a name also given to other similar vehicles.[8] In 1955, the BMW Isetta became the world's first mass-production car to achieve a fuel consumption of 3 L/100 km (94 mpg; 78 mpg).[a] It was the top-selling single-cylinder car in the world, with 161,728 units sold.[9] Initially manufactured by the Italian firm Iso SpA, the name Isetta is the Italian diminutive form of Iso, meaning "little Iso".[10] Iso Isetta (Italy) The car originated with the Italian firm of Iso SpA. In the early 1950s the company was building refrigerators, motor scooters and small three-wheeled trucks. Iso's owner, Renzo Rivolta, decided to build a small car for mass distribution.[10] By 1952 the engineers Ermenegildo Preti[11] and Pierluigi Raggi had d ...more...

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List of common physics notations

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List of common physics notations

This is a list of common physical constants and variables, and their notations. Note that bold text indicates that the quantity is a vector. Latin characters Symbol Meaning SI unit of measure A {\displaystyle A} area meter squared (m2) magnetic vector potential amplitude meter atomic mass number a {\displaystyle \mathbf {a} } acceleration meters per second squared (m/s2) B {\displaystyle \mathbf {B} } magnetic flux density also called the magnetic field density or magnetic induction tesla (T), or equivalently,weber per square meter (Wb/m2) C {\displaystyle C} capacitance farad (F) heat capacity joule per kelvin (J K−1), or equivalently, joule per degree Celsius (J °C−1) constant of integration varied depending on context c {\displaystyle c} speed of light (in vacuum) 299,792,458 meter per second (m/s) speed of sound 340.29 meter per second (m/s) specific heat capacity joule per kilogram per kelvin (J kg−1 K−1), or equivalently, joule ...more...

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.NET Framework

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.NET Framework

.NET Framework (pronounced dot net) is a software framework developed by Microsoft that runs primarily on Microsoft Windows. It includes a large class library named Framework Class Library (FCL) and provides language interoperability (each language can use code written in other languages) across several programming languages. Programs written for .NET Framework execute in a software environment (in contrast to a hardware environment) named Common Language Runtime (CLR), an application virtual machine that provides services such as security, memory management, and exception handling. (As such, computer code written using .NET Framework is called "managed code".) FCL and CLR together constitute .NET Framework. FCL provides user interface, data access, database connectivity, cryptography, web application development, numeric algorithms, and network communications. Programmers produce software by combining their source code with .NET Framework and other libraries. The framework is intended to be used by most new ...more...

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ASCII

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ASCII

ASCII ( ( listen) ASS-kee),[1]:6 abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Most modern character-encoding schemes are based on ASCII, although they support many additional characters. ASCII is the traditional name for the encoding system; the Internet Assigned Numbers Authority (IANA) prefers the updated name US-ASCII, which clarifies that this system was developed in the US and based on the typographical symbols predominantly in use there.[2] ASCII is one of a 1963 List of IEEE milestones. ASCII chart from an earlier-than 1972 printer manual (b1 is the least significant bit.) Overview ASCII was developed from telegraph code. Its first commercial use was as a seven-bit teleprinter code promoted by Bell data services. Work on the ASCII standard began on October 6, 1960, with the first meeting of the American Standards Associ ...more...

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Ring size

topic

Ring size

A Bergeon ring sizing stick. (ISO 8653:1986 and number scales) Ring size is a measurement used to denote the circumference of jewellery rings. Systems There are several systems for denoting the sizes of jewellery rings in use around the world: The ISO standard for ring sizes is ISO 8653:2016, which defines standard ring sizes in terms of the inner circumference of the ring measured in millimetres.[1] In the United States and Canada, ring sizes are specified using a numerical scale, with quarter and half sizes. An increase of a full size is an increase of 0.032 inch (0.8128 mm) in diameter, or roughly 1/10 inch (more precisely, 0.1005 in or 2.55 mm) in inside circumference. In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale, with half sizes. In India, Japan and China, ring sizes are specified using a numerical scale, that only has whole sizes, and does not have simple linear correlation with diameter or circumference. In Austria, France, Germany, Belgiu ...more...

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Arthur Bigge, 1st Baron Stamfordham

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Arthur Bigge, 1st Baron Stamfordham

Lieutenant-Colonel Arthur John Bigge, 1st Baron Stamfordham, GCB, GCIE, GCVO, KCSI, KCMG, ISO, PC (18 June 1849 – 31 March 1931) was a British Army officer and courtier. He was Private Secretary to Queen Victoria during the last few years of her reign, and to George V during most of his reign. He was the maternal grandfather of Lord Adeane, Private Secretary to Elizabeth II from 1953 to 1972. Background and education Bigge was the son of John Frederic Bigge (1814–1885) Vicar of Stamfordham, Northumberland and the grandson of Charles William Bigge (1773–1849) of Benton House, Little Benton, Newcastle on Tyne and Linden Hall, Longhorsley, Northumberland, High Sheriff of Northumberland and a prominent merchant and banker in Newcastle on Tyne. He was educated at Rossall School and the Royal Military Academy and was commissioned into the Royal Artillery in 1869.[1] Career Between 1878 and 1879 Bigge fought in the Anglo-Zulu War, it is known from the despatches he had been mentioned in. In 1880 he was warned to B ...more...

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Unicode

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Unicode

Unicode is a computing industry standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard is maintained by the Unicode Consortium, and as of June 2018 the most recent version, Unicode 11.0, contains a repertoire of 137,439 characters covering 146 modern and historic scripts, as well as multiple symbol sets and emoji. The character repertoire of the Unicode Standard is synchronized with ISO/IEC 10646, and both are code-for-code identical. The Unicode Standard consists of a set of code charts for visual reference, an encoding method and set of standard character encodings, a set of reference data files, and a number of related items, such as character properties, rules for normalization, decomposition, collation, rendering, and bidirectional display order (for the correct display of text containing both right-to-left scripts, such as Arabic and Hebrew, and left-to-right scripts).[1] Unicode's success at unifying character sets has ...more...

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Extended ASCII

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Extended ASCII

Output of the program ascii in Cygwin Extended ASCII (EASCII or high ASCII) character encodings are eight-bit or larger encodings that include the standard seven-bit ASCII characters, plus additional characters. The use of the term is sometimes criticized,[1][2][3] because it can be mistakenly interpreted to mean that the ASCII standard has been updated to include more than 128 characters or that the term unambiguously identifies a single encoding, neither of which is the case. There are many extended ASCII encodings (more than 220 DOS and Windows codepages). EBCDIC ("the other" major 8-bit character code) likewise developed many extended variants (more than 186 EBCDIC codepages) over the decades. Motive ASCII was designed in the 1960s for teleprinters and telegraphy, and some computing. Early teleprinters were electromechanical, having no microprocessor and just enough electromechanical memory to function. They fully processed one character at a time, returning to an idle state immediately afterward. Th ...more...

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Horsepower

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Horsepower

One metric horsepower is needed to lift 75 kilograms by 1 metre in 1 second Horsepower (hp) is a unit of measurement of power (the rate at which work is done). There are many different standards and types of horsepower. Two common definitions being used today are the mechanical horsepower (or imperial horsepower), which is about 745.7 watts, and the metric horsepower, which is approximately 735.5 watts. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses. It was later expanded to include the output power of other types of piston engines, as well as turbines, electric motors and other machinery.[1][2] The definition of the unit varied among geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on January 1, 2010, the use of horsepower in the EU is permitted only as a supplementary unit.[3] History A team of six horses m ...more...

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MQTT

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MQTT

MQTT[1] (Message Queuing Telemetry Transport) is an ISO standard (ISO/IEC PRF 20922)[2] publish-subscribe-based messaging protocol. It works on top of the TCP/IP protocol. It is designed for connections with remote locations where a "small code footprint" is required or the network bandwidth is limited. The publish-subscribe messaging pattern requires a message broker. Andy Stanford-Clark of IBM and Arlen Nipper of Cirrus Link authored the first version of the protocol in 1999.[3] The specification does not specify the meaning of "small code footprint" or the meaning of "limited network bandwidth". Thus, the protocol's availability for use depends on the context. In 2013, IBM submitted MQTT v3.1 to the OASIS specification body with a charter that ensured only minor changes to the specification could be accepted.[4] MQTT-SN[5] is a variation of the main protocol aimed at embedded devices on non-TCP/IP networks, such as ZigBee. Historically, the "MQ" in "MQTT" came from IBM's MQ Series message queuing produc ...more...

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Code page

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Code page

In computing, a code page is a table of values that describes the character set used for encoding a particular set of characters, usually combined with a number of control characters. The term "code page" originated from IBM's EBCDIC-based mainframe systems,[1] but Microsoft, SAP,[2] and Oracle Corporation[3] are among the few vendors which use this term. The majority of vendors identify their own character sets by a name. In the case when there is a plethora of character sets (like in IBM), identifying character sets through a number is a convenient way to distinguish them. Originally, the code page numbers referred to the page numbers in the IBM standard character set manual,[4][5][6] a condition which has not held for a long time. Vendors that use a code page system allocate their own code page number to a character encoding, even if it is better known by another name; for example, UTF-8 has been assigned page numbers 1208 at IBM, 65001 at Microsoft, and 4110 at SAP. Hewlett-Packard uses a similar concep ...more...

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ELM327

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ELM327

The ELM327 is a programmed microcontroller produced by ELM Electronics for translating the on-board diagnostics (OBD) interface found in most modern cars. The ELM327 command protocol is one of the most popular PC-to-OBD interface standards and is also implemented by other vendors. The original ELM327 is implemented on the PIC18F2480 microcontroller from Microchip Technology. ELM327 is one of a family of OBD translators from ELM Electronics. Other variants implement only a subset of the OBD protocols. Uses The ELM327 abstracts the low-level protocol and presents a simple interface that can be called via a UART, typically by a hand-held diagnostic tool or a computer program connected by USB, RS-232, Bluetooth or Wi-Fi. New applications include smartphones. There are a large number of programs available that connect to the ELM327.[1] The function of such software may include Supplementary vehicle instrumentation Reporting of error codes Clearing error codes ELM327 Functions Read diagnostic trouble c ...more...

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thesis'

(ChinesePrimes)

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Advanced Audio Coding

topic

Advanced Audio Coding

Advanced Audio Coding (AAC) is a proprietary audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at the same bit rate.[2] The confusingly named AAC+ (HE-AAC) does so only at low bit rates and less so at high ones. AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4 specifications.[3][4] Part of AAC, HE-AAC (AAC+), is part of MPEG-4 Audio and also adopted into digital radio standards DAB+ and Digital Radio Mondiale, as well as mobile television standards DVB-H and ATSC-M/H. AAC supports inclusion of 48 full-bandwidth (up to 96 kHz) audio channels in one stream plus 16 low frequency effects (LFE, limited to 120 Hz) channels, up to 16 "coupling" or dialog channels, and up to 16 data streams. The quality for stereo is satisfactory to modest requirements at 96 kbit/s in joint stereo mode; however, hi-fi transparency demands data rates of at least 128 kbit/s (VBR). Tests of MPEG-4 aud ...more...

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ISO 3166-2:JP

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ISO 3166-2:JP

ISO 3166-2:JP is the entry for Japan in ISO 3166-2, part of the ISO 3166 standard published by the International Organization for Standardization (ISO), which defines codes for the names of the principal subdivisions (e.g.provinces or states) of all countries coded in ISO 3166-1. Currently for Japan, ISO 3166-2 codes are defined for 47 prefectures. Each code consists of two parts, separated by a hyphen. The first part is JP, the ISO 3166-1 alpha-2 code of Japan. The second part is two digits (01–47), which is the Japanese Industrial Standard JIS X 0401 code of the prefecture. The codes are assigned roughly from north to south. Current codes Subdivision names are listed as in the ISO 3166-2 standard published by the ISO 3166 Maintenance Agency (ISO 3166/MA). Map of Japan with each prefecture labelled with the second part of its ISO 3166-2 code (with leading digit 0 omitted). Code Subdivision name (jp) Subdivision name (en) JP-23  Aiti Aichi JP-05  Akita Akita JP-02  Aomori Aomori JP-3 ...more...

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Data Matrix

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Data Matrix

An example of a Data Matrix code, encoding the text: "Wikipedia, the free encyclopedia" A Data Matrix is a two-dimensional barcode consisting of black and white "cells" or modules arranged in either a square or rectangular pattern, also known as a matrix. The information to be encoded can be text or numeric data. Usual data size is from a few bytes up to 1556 bytes. The length of the encoded data depends on the number of cells in the matrix. Error correction codes are often used to increase reliability: even if one or more cells are damaged so it is unreadable, the message can still be read. A Data Matrix symbol can store up to 2,335 alphanumeric characters. Data Matrix symbols are rectangular, usually square in shape and composed of square "cells" which represent bits. Depending on the coding used, a "light" cell represents a 0 and a "dark" cell is a 1, or vice versa. Every Data Matrix is composed of two solid adjacent borders in an "L" shape (called the "finder pattern") and two other borders consisting ...more...

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Windows-1252

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Windows-1252

Windows-1252, sometimes incorrectly called "ANSI" or "ASCII". Red indicates code points that are C1 control codes in ISO-8859-1. Blue dots indicate control codes or unused code points. Windows-1252 or CP-1252 (code page – 1252) is a 1 byte character encoding of the Latin alphabet, used by default in the legacy components of Microsoft Windows in English and some other Western languages (other languages use different default encodings). It is probably the most-used 8-bit character encoding in the world. As of April 2018, 0.7% of all web sites declared use of Windows-1252,[1][2] but at the same time 4.1% used ISO 8859-1,[1] which by HTML5 standards should be considered the same encoding, so that 4.8% of web sites effectively used Windows-1252. In addition most web browsers will correctly render it if encountered in text that claims to be UTF-8, so its actual usage may be higher. Details This character encoding is a superset of ISO 8859-1 in terms of printable characters, but differs from the IANA's ISO-8859- ...more...

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ISO 13567

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ISO 13567

ISO 13567 is an international Computer-aided design (CAD) layer standard. Standard parts The standard is divided into three parts: ISO 13567-1:2017[1] Technical product documentation — Organization and naming of layers for CAD — Part 1: Overview and principles ISO 13567-2:2017[2] Technical product documentation — Organization and naming of layers for CAD — Part 2: Concepts, format and codes used in construction documentation ISO/TR 13567-3:1999 (withdrawn September 2015)[3] Technical product documentation — Organization and naming of layers for CAD — Part 3: Application of ISO 13567-1 and ISO 13567-2 Standard has been developed by Technical Committee TC 10 (Technical product documentation) Subcommittee SC 8 (Construction documentation); Refer. ICS: 01.110; 35.240.10. Structure of layer names CAD layer names are structured as a series of mandatory and optional fixed length fields, composed as a continuous alpha-numerical text string. Mandatory fields Agent responsible (2 characters, indic ...more...

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C99

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C99

Cover of the C99 standards document C99 (previously known as C9X) is an informal name for ISO/IEC 9899:1999, a past version of the C programming language standard.[1] It extends the previous version (C90) with new features for the language and the standard library, and helps implementations make better use of available computer hardware, such as the IEEE 754-1985 arithmetic, and compiler technology.[2] The C11 version of the C programming language standard, published in 2011, replaces C99. History After ANSI produced the official standard for the C programming language in 1989, which became an international standard in 1990, the C language specification remained relatively static for some time, while C++ continued to evolve, largely during its own standardization effort. Normative Amendment 1 created a new standard for C in 1995, but only to correct some details of the 1989 standard and to add more extensive support for international character sets. The standard underwent further revision in the late 1990 ...more...

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ISO 20400

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ISO 20400

ISO 20400 Sustainable procurement -- Guidance [1] provides guidance to organizations, independent of their activity or size, on integrating sustainability within procurement. It is intended for stakeholders involved in, or impacted by, procurement decisions and processes. This standard was developed by ISO project committee ISO/PC 277. History The standard was developed by project committee ISO/PC 277, which started work in the year 2013. The first edition of ISO 20400 was published on 21 April 2017.[2] Main requirements of the standard The ISO 20400:2017 adopts the structure in the following breakdown: 1 Scope 2 Normative references 3 Terms and definitions 4 Understanding the fundamentals 5 Integrating sustainability into the organization's procurement policy and strategy 6 Organizing the procurement function toward sustainability 7 Integrating sustainability into the procurement process See also Quality management system List of ISO standards Conformity assessment International Organization ...more...

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Standards in the Petroleum Industry

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Preferred metric sizes

topic

Preferred metric sizes

Preferred metric sizes are a set of international standards and de facto standards that are designed to make using the metric system easier and simpler, especially in engineering and construction practices. One of the methods used to arrive at these preferred sizes is the use of preferred numbers and convenient numbers such as the Renard series, the 1-2-5 series to limit the number of different sizes of components needed. One of the largest benefits of such limits is an ensuing multiplicative or exponential reduction in the number of parts, tools and other items needed to support the installation and maintenance of the items built using these techniques. This occurs because eliminating one diameter fastener will typically allow the elimination of a large number of variations on that diameter (multiple thread pitches, multiple lengths, multiple tip types, multiple head types, multiple drive types, and the tools needed for installing each, including multiple drill bits (one for each different thread pitch, mat ...more...

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31 (number)

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31 (number)

31 (thirty-one) is the natural number following 30 and preceding 32. In mathematics 31 is the number of regular polygons with an odd number of sides that are known to be constructible with compass and straightedge. 31 is the third Mersenne prime (25 − 1)[1] and the eighth Mersenne prime exponent, as well as the fourth primorial prime, and together with twenty-nine, another primorial prime, it comprises a twin prime. As a Mersenne prime, 31 is related to the perfect number 496, since 496 = 2(5 − 1)(25 − 1). 31 is also the 4th lucky prime[2] and the 11th supersingular prime.[3] 31 is a centered triangular number,[4] the lowest prime centered pentagonal number[5] and a centered decagonal number.[6] For the Steiner tree problem, 31 is the number of possible Steiner topologies for Steiner trees with 4 terminals. At 31, the Mertens function sets a new low of −4, a value which is not subceded until 110. 31 is a centered pentagonal number No integer added up to its base 10 digits results in 31, making 31 ...more...

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