B. Defining Function and Control Keys : FRS Mapping Objects : FRS Keys
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FRS Keys
FRS keys enable you to map function and control keys (including arrow keys)directly to a program operation. While a function, control, or arrow key can always map to a menu item operation by position, you can map the key directly to the operation itself.
For instance, you might not want every operation to appear as a menu item, particularly if the operation is available across all the frames in an application. By requiring that certain repeated operations be invoked only through function or control or arrow keys, you can shorten long menu lines and use the menu primarily for operations that are unique to each frame.
Because not all keyboards have the same set of function keys, it makes little sense to assign an operation directly to a particular key inside an application. Instead, you equate operations with logical FRS keys. The FRS keys can then be mapped to function, control, or arrow keys at any of the four mapping levels.
FRS keys invoke operations only when specified in the application. A mapping file, by itself, merely assigns the FRS key to a function or control or arrow key; it cannot define the meaning of the FRS key. A FRS key must be equated with an operation when you write the application. For instructions on how to do this, see the Forms-based Application Development Tools User Guide. The Ingres forms-based tools also use FRS keys extensively. For more information, see Predefined FRS Keys (see page Predefined FRS Keys).
You can define the same operation for both a menu item and a FRS key. The end user can then activate the operation either with the key that is mapped to the menu item's position or with the key that is mapped to the FRS key. This means the user is always be able to invoke the menu item with the same function key, even if the item's position on the menu line changes from frame to frame. Whenever an operation has been associated with both a menu item and an FRS key, the label for the menu item indicates the function or control or arrow key that maps to the corresponding FRS key, not the function or control or arrow key that maps to the item's position on the line.