Scroll Lock (⤓ or ⇳) is a lock key (typically with an associated status light) on most IBM-compatible computer keyboards. Depending on the operating system, it may be used for different purposes, and applications may assign functions to the key or change their behavior depending on its toggling state. The key is not frequently used, and therefore some reduced or specialized keyboards lack altogether. Pressing performs the same function as pressing . This behavior is a remnant of the original IBM PC keyboards, which did not have a dedicated key. Instead, they assigned the Pause function to and the Break function to . Function Window scrolling The key was meant to lock all scrolling techniques, and is a vestige of the original IBM PC keyboard. In the original design, was intended to modify the behavior of the arrow keys. When the mode was on, the arrow keys would scroll the contents of a text window instead of moving the cursor. In this usage, is a toggling lock key like Num Lock or Caps Lock, which have a state that persists after the key is released. Today, this particular use of is rare. Modern programs honoring this behavior include IBM Lotus Notes, Forté Agent, Image-Line FL Studio, Renoise, Microsoft Excel, Microsoft Project, LibreOffice Calc, and occasionally Microsoft Word. Some text editors (such as Notepad++, Microsoft Visual Studio) exhibit similar behavior when the arrow keys are used with pressed. Most GUI environments neglect , which means scrolling must be accomplished with a mouse, using means such as scrollbars or scroll wheels. Often, the middle of the wheel mouse button works as a toggle determining if mouse movements will move the mouse cursor or scroll the contents in the scroll window. Some web browsers including Google Chrome, Firefox, and Internet Explorer support a Caret browsing mode which can be toggled by . While the window scrolling behavior with Caret navigation disabled (the default) is similar to that suggested for Scroll Lock, enabling Caret navigation will enable a cursor scrolling behavior as if Scroll Lock were disabled. Console scrolling Pressing the key in the Linux console while the text is scrolling through the screen freezes the console output (but not input) during which no further text is sent to the screen, while the program continues running as usual. When is pressed again, the screen is unfrozen and all text generated during the freeze is