National Teaching and Learning Change ProgrammeInformation and Communication Technology:
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• Reverse Polish Notation
  Reverse Polish notation is a form of postfix notation where brackets are not permitted (and not needed). No rules about precedence are needed for different operations, which are carried out in the order met in the expression. Reverse Polish notation has the advantage that any algebraic expression can be processed strictly from left to right. It is widely used by compilers which convert the infix notation that a programmer has used into reverse Polish notation. This reverse Polish notation is then easily converted into a machine-code program. It was devised by the Polish mathematician Jan Lukasiewicz.
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• rewind
  To go back to the beginning of a multimedia file.
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• RGB
  Red, green, blue. In graphics, web design and design for computer monitors, colours are defined in terms of a combination of these three colours.
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• right click
  Most mouse actions use the left hand button. However, depending on the program, clicking the right mouse button will perform certain actions, e.g. displaying a small pop-up menu.
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• ring network
  In a local area network, a ring network has each of the devices on the network connected to a ring (or loop) communications line around which signals are sent.
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• robot
  An automated program that follows hypertext links and then performs some action, e.g. indexing the words on a website.
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• rogue value
  A rogue value is a specified value, not normally expected in the data, that is used to mark the end of a list of data items. The program can process the data in order until it reaches the value. The number of data items can vary and does not have to be known in advance. The term rogue value often implies a numeric value. It may also describe a special value, at some point in the data, used to indicate a particular situation, for example a deleted record.
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• rollover
  The effect achieved by changing the appearance of an image when the mouse pointer moves over it.
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• rotate
  In graphics, to turn an image clockwise or anti-clockwise.
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• rounding
  The approximation of a numeric data item by its nearest equivalent, to a given number of significant figures or decimal places. For example, 1.36 rounded to one decimal place is 1.4.
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• router
  In a network, routers are sophisticated switched hubs. They hold information about the addresses of computers attached to the network and can forward data efficiently to the correct location via an appropriate route. They are generally used as gateways where a local area network is connected to a larger network such as the internet.
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• row
  A horizontal line of cells in a spreadsheet or table. In a spreadsheet, each row is identified by a number.
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• RSS
  Rich Site Summary or Really Simple Syndication. A way of subscribing to a website so that you automatically get notified when new information appears there.
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• ruler
  Often used in graphics packages, word processors, etc., to display a ruler on screen to aid the precise alignment of text boxes, graphics, etc.
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• run
  To run a program is to load it and start executing it.
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• run-time
  The time during which a program is being executed.
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• run-time error
  Errors which occur during program execution. These errors, such as overflow and division by zero, can occur if a mistake is made in the program logic or as a result of external effects not catered for by the program, such as lack of memory or unusual data.