這個圖標是由 The International Electrotechnical Commission (IEC) 制定的。 * IEC 官網：Welcome to the IEC * IEC ＝ 國際電工委員會，不知道這麼翻譯對不對……
IEC 5007, the power on (line) symbol, appearing on a button or one end of a toggle switch indicates that the control places the equipment into a fully powered state. It comes from the binary system (1 or | means on)
代表開啟（連接）
IEC 5008, the power off (circle) symbol on a button or toggle, indicates that using the control will disconnect power to the device. It comes from the binary system (0 means off)
代表關閉（斷開）
IEC 5010, the power on-off symbol (line within a circle), is used on buttons that switch a device between on and fully off states. 代表可以切換開/關狀態的按鈕。
IEC 5009, the standby symbol (line partially within a broken circle), indicates a sleep mode or low power state.代表睡眠模式或者低電量運行
The switch does not fully disconnect the device from its power supply. This may appear on a toggle switch opposite a power on symbol, alone on a pushbutton that places the device into a standby state, or alone on a button that switches between on and standby.
這就是我們熟悉的 開關按鈕
A crescent moon, indicating sleep, is added by IEEE 1621 as a replacement for the standby symbol.
專業搬磚手！！！ 電源早在二戰期間，工程師用二進位系統來標識電源按鈕：1代表「開」，0代表「關」。1973年，國際電工委員會（IEC）把一個「開口處有條線嵌入的圓圈」粗略地定義為「standby power state（待機電源狀態）」，並且一直沿用至今。但是，IEEE認為這個符號非常含糊，故把它定義為「Power（電源）」。
