5.2. PHIGURE INPUT CLASSES

An input device is identified by a workstation identifier, an input class and a device number. The workstation identifier indicates to which workstation the input device is associated. The input class determines the type of input values delivered by the input device. The six input classes and the input values supplied are:

• 1) LOCATOR - a position in WC and a view index
• 2) STROKE - a sequence of points in WC and a view index
• 3) VALUATOR - a real number
• 4) CHOICE - a selection state and a positive integer number which represents a selection from a set of choices
• 5) PICK - a designation state and a pick path
• 6) STRING - a character string

The device number differentiates the input devices belonging to the same class on the same workstation.

A physical device may belong to one or more input classes. The input classes to which a device belongs are determined both by the device input characteristics and the application user interface design.

The following examples are physical devices which may be used to implement the different input classes:

LOCATOR Mouse, Tablet

STROKE Mouse, Digitizing tablet

VALUATOR Keyboard, Mouse cursor, Bank of control knobs

CHOICE Keyboard, Mouse menu, Function keys

PICK Mouse

STRING Workstation keyboard