As the voice of the U.S. standards and conformity assessment system, the American National Standards Institute (ANSI) empowers its members and constituents to strengthen the U.S. marketplace position in the global economy while helping to assure the safety and health of consumers and the protection of the environment.
The Institute oversees the creation, promulgation and use of thousands of norms and guidelines that directly impact businesses in nearly every sector: from acoustical devices to construction equipment, from dairy and livestock production to energy distribution, and many more.
ANSI is also actively engaged in accreditation - assessing the competence of organizations determining conformance to standards.
To enhance both the global competitiveness of U.S. business and the U.S. quality of life by promoting and facilitating voluntary consensus standards and conformity assessment systems, and safeguarding their integrity.
ASCII abbreviated from American Standard Code for Information Interchange, is a character-encoding scheme (the IANA prefers the name US-ASCII).
ASCII codes represent text in computers, communications equipment, and other devices that use text.
Most modern character-encoding schemes are based on ASCII, though they support many additional characters.
ASCII was the most common character encoding on the World Wide Web until December 2007, when it was surpassed by UTF-8, which is fully backward compatibe to ASCII.
ASCII developed from telegraphic codes.
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 Association's (ASA) X3.2 subcommittee.
The first edition of the standard was published during 1963, underwent a major revision during 1967, and experienced its most recent update during 1986.
Compared to earlier telegraph codes, the proposed Bell code and ASCII were both ordered for more convenient sorting (i.e., alphabetization) of lists, and added features for devices other than teleprinters.
Originally based on the English alphabet, ASCII encodes 128 specified characters into seven-bit integers as shown by the ASCII chart below.
The characters encoded are numbers 0 to 9, lowercase letters a to z, uppercase letters A to Z, basic punctuation symbols, control codes that originated with Teletype machines, and a space.
For example, lowercase j would become binary 1101010 and decimal 106.
ASCII includes definitions for 128 characters: 33 are non-printing control characters (many now obsolete) that affect how text and space are processed and 95 printable characters, including the space (which is considered an invisible graphic).
In mathematics and computer science, an algorithm is a self-contained step-by-step set of operations to be performed.
Algorithms exist that perform calculation, data processing, and automated reasoning.
The words 'algorithm' and 'algorism' come from the name al-Khwarizmi. Al-Khwarizmi (c. 780-850) was a Persian mathematician, astronomer, geographer, and scholar.
An algorithm is an effective method that can be expressed within a finite amount of space and time and in a well-defined formal language for calculating a function.
Starting from an initial state and initial input (perhaps empty), the instructions describe a computation that, when executed, proceeds through a finite number of well-defined successive states, eventually producing "output" and terminating at a final ending state.
The transition from one state to the next is not necessarily deterministic; some algorithms, known as randomized algorithms, incorporate random input.
The concept of algorithm has existed for centuries, however a partial formalization of what would become the modern algorithm began with attempts to solve the Entscheidungsproblem (the "decision problem") posed by David Hilbert in 1928.
Subsequent formalizations were framed as attempts to define "effective calculability" or "effective method"; those formalizations included the Gödel–Herbrand–Kleene recursive functions of 1930, 1934 and 1935, Alonzo Church's lambda calculus of 1936, Emil Post's "Formulation 1" of 1936, and Alan Turing's Turing machines of 1936–7 and 1939.
Giving a formal definition of algorithms, corresponding to the intuitive notion, remains a challenging problem.
What is an algorithm and why should you care?
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In mathematics and mathematical logic, Boolean algebra is the branch of algebra in which the values of the variables are the truth values true and false, usually denoted 1 and 0 respectively.
Instead of elementary algebra where the values of the variables are numbers, and the main operations are addition and multiplication, the main operations of Boolean algebra are the conjunction and the disjunction or and the negation not, denoted ¬.
It is thus a formalism for describing logical relations in the same way that ordinary algebra describes numeric relations.
Boolean algebra was introduced by George Boole in his first book The Mathematical Analysis of Logic (1847), and set forth more fully in his
An Investigation of the Laws of Thought (1854).
According to Huntington, the term "Boolean algebra" was first suggested by Sheffer in 1913.
Boolean algebra has been fundamental in the development of digital electronics, and is provided for in all modern programming languages.
It is also used in set theory and statistics.
Cloud storage is a model of data storage in which the digital data is stored in logical pools, the physical storage spans multiple servers (and often locations), and the physical environment is typically owned and managed by a hosting company.
These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running.
People and organizations buy or lease storage capacity from the providers to store user, organization, or application data.
Cloud storage services may be accessed through a co-located cloud computer service, a web service application programming interface (API) or by applications that utilize the API, such as cloud desktop storage, a cloud storage gateway or Web-based content management systems.
In telecommunications, a communications protocol is a system of rules that allow two or more entities of a communications system to transmit information via any kind of variation of a physical quantity.
These are the rules or standard that defines the syntax, semantics and synchronization of communication and possible error recovery methods.
Protocols may be implemented by hardware, software, or a combination of both.
Communicating systems use well-defined formats (protocol) for exchanging messages.
Each message has an exact meaning intended to elicit a response from a range of possible responses pre-determined for that particular situation.
The specified behavior is typically independent of how it is to be implemented.
Communications protocols have to be agreed upon by the parties involved.
To reach agreement, a protocol may be developed into a technical standard.
A programming language describes the same for computations, so there is a close analogy between protocols and programming languages: protocols are to communications as programming languages are to computations.
In cryptography, encryption is the process of encoding messages or information in such a way that only authorized parties can read it.
Encryption does not of itself prevent interception, but denies the message content to the interceptor.
In an encryption scheme, the intended communication information or message, referred to as plaintext, is encrypted using an encryption algorithm, generating ciphertext that can only be read if decrypted.
For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm.
It is in principle possible to decrypt the message without possessing the key, but, for a well-designed encryption scheme, large computational resources and skill are required.
An authorized recipient can easily decrypt the message with the key provided by the originator to recipients, but not to unauthorized interceptors.
Symmetric key encryption
In symmetric-key schemes,the encryption and decryption keys are the same. Communicating parties must have the same key before they can achieve secure communication.
Public key encryption
Illustration of how encryption is used within servers Public key encryption.
In public-key encryption schemes, the encryption key is published for anyone to use and encrypt messages.
However, only the receiving party has access to the decryption key that enables messages to be read.
Public-key encryption was first described in a secret document in 1973; before then all encryption schemes were symmetric-key (also called private-key).
A publicly available public key encryption application called Pretty Good Privacy (PGP) was written in 1991 by Phil Zimmermann, and distributed free of charge with source code; it was purchased by Symantec in 2010 and is regularly updated.
Explorer++ is a free and open-source navigational file manager for Microsoft Windows.
It features multi-tabbed panes, bookmarks menu, and a customizable user interface.
It can be configured to run portably or use the registry.
It can also be set to replace Windows Explorer as the default file manager.
File Explorer, previously known as Windows Explorer, is a file manager application that is included with releases of the Microsoft Windows operating system from Windows 95 onwards.
It provides a graphical user interface for accessing the file systems.
It is also the component of the operating system that presents many user interface items on the monitor such as the taskbar and desktop.
Controlling the computer is possible without Windows Explorer running (for example, the File | Run command in Task Manager on NT-derived versions of Windows will function without it, as will commands typed in a command prompt window).
Located in the C:\Windows directory, it is sometimes referred to as the Windows shell, explorer.exe, or simply "Explorer".
In computing, a file system (or filesystem) is used to control how data is stored and retrieved.
Without a file system, information placed in a storage area would be one large body of data with no way to tell where one piece of information stops and the next begins.
By separating the data into individual pieces, and giving each piece a name, the information is easily separated and identified.
Taking its name from the way paper-based information systems are named, each group of data is called a "file".
The structure and logic rules used to manage the groups of information and their names is called a "file system".
There are many different kinds of file systems.
Each one has different structure and logic, properties of speed, flexibility, security, size and more.
Some file systems have been designed to be used for specific applications.
For example, the ISO 9660 file system is designed specifically for optical discs.
File systems can be used on many different kinds of storage devices.
Each storage device uses a different kind of media.
The most common storage device in use today is a hard drive whose media is a disc that has been coated with a magnetic film.
The film has ones and zeros 'written' on it by sending electrical pulses to a magnetic "read-write" head.
Other media that are used are magnetic tape, optical disc, and flash memory.
In some cases, such as with tmpfs, the computer's main memory (RAM) is used to create a temporary file system for short-term use.
Some file systems are used on local data storage devices; others provide file access via a network protocol (for example, NFS, SMB, or 9P clients).
Some file systems are "virtual", in that the "files" supplied are computed on request (e.g. procfs) or are merely a mapping into a different file system used as a backing store.
The file system manages access to both the content of files and the metadata about those files.
It is responsible for arranging storage space; reliability, efficiency, and tuning with regard to the physical storage medium are important design considerations.
A filename (or file name) is used to identify a storage location in the file system.
Most file systems have restrictions on the length of filenames.
In some file systems, filenames are not case sensitive (i.e., filenames such as FOO and foo refer to the same file); in others, filenames are case sensitive (i.e., the names FOO, Foo and foo refer to three separate files).
Most modern file systems allow filenames to contain a wide range of characters from the Unicode character set.
However, they may have restrictions on the use of certain special characters, disallowing them within filenames; those characters might be used to indicate a device, device type, directory prefix, file path separator, or file type.
File systems typically have directories (also called folders) which allow the user to group files into separate collections.
This may be implemented by associating the file name with an index in a table of contents or an inode in a Unix-like file system.
Directory structures may be flat (i.e. linear), or allow hierarchies where directories may contain subdirectories.
The first file system to support arbitrary hierarchies of directories was used in the Multics operating system.
The native file systems of Unix-like systems also support arbitrary directory hierarchies, as do, for example, Apple's
Hierarchical File System, and its successor HFS+ in classic Mac OS (HFS+ is still used in Mac OS X), the FAT file system in MS-DOS 2.0 and later versions of MS-DOS and in Microsoft Windows, the NTFS file system in the Windows NT family of operating systems, and the ODS-2 (On-Disk Structure-2) and higher levels of the Files-11 file system in OpenVMS.
Google Drive is a file storage and synchronization service created by Google.
It allows users to store files in the cloud, share files, and edit documents, spreadsheets, and presentations with collaborators.
Google Drive encompasses Google Docs, Sheets, and Slides, an office suite that permits collaborative editing of documents, spreadsheets, presentations, drawings, forms, and more.
Google Drive was launched on April 24, 2012 and had 240 million monthly active users as of October 2014.
The following articles contain lists of network protocols in various formats.
Regular Expressions at DMOZ
Visual Regular Expression
In theoretical computer science and formal language theory, a regular expression (sometimes called a rational expression) is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. "find and replace"-like operations.
The concept arose in the 1950s, when the American mathematician Stephen Kleene formalized the description of a regular language, and came into common use with the Unix text processing utilities ed, an editor, and grep, a filter.
In modern usage, "regular expressions" are often distinguished from the derived, but fundamentally distinct concepts of regex or regexp, which no longer describe a regular language.
Regexps are so useful in computing that the various systems to specify regexps have evolved to provide both a basic and extended standard for the grammar and syntax; modern regexps heavily augment the standard.
Regexp processors are found in several search engines, search and replace dialogs of several word processors and text editors, and in the command lines of text processing utilities, such as sed and AWK.
Most other languages offer regexps via a library.
UTF-8 is a character encoding
capable of encoding all possible characters, or code points, in Unicode.
Wikipedia rfc3629 Complete Character List for UTF-8
The encoding is variable-length and uses 8-bit code units.
It was designed for backward compatibility with ASCII, and to avoid the complications of endianness and byte order marks in the alternative UTF-16 and UTF-32 encodings.
The name is derived from: Universal Coded Character Set + Transformation Format – 8-bit.
Graph indicates that UTF-8 (light blue) exceeded other main encodings of text on the Web, that by 2010 it was nearing 50% prevalent.
Encodings were detected by examining the text, not from the encoding tag in the header, and were sorted to the least inclusive set; thus, ASCII text tagged as UTF-8 or ISO-8859-1 is identified as ASCII.
By January 2016, the declared usage was up to 86.4%.
UTF-8 is the dominant character encoding for the World Wide Web, accounting for 86.4% of all Web pages in January 2016 (with the most popular East Asian encoding, GB 2312, at 0.9% and Shift JIS at 1.1%).
The Internet Mail Consortium (IMC) recommends that all e-mail programs be able to display and create mail using UTF-8, and the W3C recommends UTF-8 as the default encoding in XML and HTML.
UTF-8 encodes each of the 1,112,064 valid code points in the Unicode code space (1,114,112 code points minus 2,048 surrogate code points) using one to four 8-bit bytes (a group of 8 bits is known as an octet in the Unicode Standard).
Code points with lower numerical values (i.e., earlier code positions in the Unicode character set, which tend to occur more frequently) are encoded using fewer bytes.
The first 128 characters of Unicode, which correspond one-to-one with ASCII, are encoded using a single octet with the same binary value as ASCII, making valid ASCII text valid UTF-8-encoded Unicode as well.
And ASCII bytes do not occur when encoding non-ASCII code points into UTF-8, making UTF-8 safe to use within most programming and document languages that interpret certain ASCII characters in a special way, e.g. as end of string.
The official IANA code for the UTF-8 character encoding is UTF-8.
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