Electronic programming guides (EPGs) and interactive programming guides (IPGs) are menu-based systems that provide users of television, radio and other media applications with continuously updated menus that display scheduling information for current and upcoming broadcast programming (most commonly, TV listings). Some guides also feature backward scrolling to promote their catch up content. They are commonly known as guides or TV guides. Non-interactive electronic programming guides (sometimes known as "navigation software") are typically available for television and radio, and consist of a digitally displayed, non-interactive menu of programming scheduling information shown by a cable or satellite television provider to its viewers on a dedicated channel. EPGs are transmitted by specialized video character generation (CG) equipment housed within each such provider's central headend facility. By tuning into an EPG channel, a menu is displayed that lists current and upcoming television shows on all available channels. A more modern form of the EPG, associated with both television and radio broadcasting, is the interactive [electronic] programming guide (IPG, though often referred to as EPG). An IPG allows television viewers and radio listeners to navigate scheduling information menus interactively, selecting and discovering programming by time, title, channel or genre using an input device such as a keypad, computer keyboard or television remote control. Its interactive menus are generated entirely within local receiving or display equipment using raw scheduling data sent by individual broadcast stations or centralized scheduling information providers. A typical IPG provides information covering a span of seven or 14 days. Data used to populate an interactive EPG may be distributed over the Internet, either for a charge or free of charge, and implemented on equipment connected directly or through a computer to the Internet. Television-based IPGs in conjunction with Programme Delivery Control (PDC) technology can also facilitate the selection of TV shows for recording with digital video recorders (DVRs), also known as personal video recorders (PVRs).