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In computing, a Control key is a modifier key which, when pressed in conjunction with another key, performs a special operation (for example, ); similar to the Shift key, the Control key rarely performs any function when pressed by itself. The Control key is located on or near the bottom left side of most keyboards (in accordance with the international standard ISO/IEC 9995-2), with many featuring an additional one at the bottom right. It is usually labeled (rarely, or is seen) on keyboards which use English abbreviations for key labeling. Abbreviations in the language of the keyboard layout also are in use. e.g. the German layout uses as required by the German standard DIN 2137:2012-06. Also, there is a standardized keyboard symbol (to be used when Latin lettering is not preferred), given in ISO/IEC 9995-7 as symbol 26, and in ISO 7000 ''“Graphical symbols for use on equipment”'' as symbol ISO-7000-2028. This symbol is encoded in Unicode as U+2388 (⎈). == History == On teletypewriters and early keyboards, holding down the Control key while pressing another key zeroed the leftmost two bits of the seven bits in the generated ASCII character. This allowed the operator to produce the first 32 characters in the ASCII table. These are non-printing characters that signal the computer to control where the next character will be placed on the display device, eject a printed page or erase the screen, ring the terminal bell, or some other operation. Aptly, these characters are also called ''control characters''. Using the key with either lowercase letters (e.g. ) or uppercase letters () will generate the same ASCII code on a teletypewriter because holding down the control key grounds (zeros the voltage on) the two wires used to carry the leftmost two bits from the keyboard, ignoring their modification by the key. In modern computers, the interpretation of keypresses is generally left to the software. Modern keyboards distinguish each physical key from every other and report all keypresses and releases to the controlling software. This additional flexibility is not often taken advantage of and it usually does not matter, for example, whether the control key is pressed in conjunction with an upper or a lower case character. When the original purpose of the ASCII control characters became either obsolete or seldom used, later software appropriated the Control key combinations for other purposes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「control key」の詳細全文を読む スポンサード リンク
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