Power symbol

A power symbol is a symbol indicating that a control activates or deactivates a particular device. Universal power symbols are described in the International Electrotechnical Commission 60417 standard, Graphical symbols for use on equipment, appearing in the 1973 edition of the document (as IEC 417) and informally used earlier.

The well known on/off power symbol was the result of the logical evolution in user interface design. Originally, most early power controls consisted of switches that were toggled between two states demarcated by the words On and Off. As technology became more ubiquitous, these English words were replaced by the universal numeral symbols 1 and 0 (typically without serifs) to bypass language barriers. This "1" and "0" standard is still used on toggle power switches.

To create the symbol for a single on/off button, the "1" and "0" symbols were super-imposed onto each other to create the universally recognized power symbol used today. Because of widespread use of this symbol, a campaign was launched to add the set of characters to Unicode. In February 2015, the proposal was accepted by Unicode and as of late 2015 the IEC power symbol family was in Stage 7 of Unicode character development and "either in ISO approval ballot or pending ISO publication." The symbols are scheduled to be included in Unicode 9.0, which is set to be released in June 2016. It will be in the "Miscellaneous Technical" block, with code points 23FB-FE.