• Control functions: used for starting (initializing) and stopping (terminating) GDDM processing, for controlling device input/output, and for providing some general services.

• Copy functions: used for copying (or sending) the contents of the current page, a graphics field, or an image field to a device other than the primary device.

• Device functions: used for describing a device to GDDM, and for querying the device characteristics.

• Graphics functions: used for creating, displaying and modifying pictures. The pictures are built up from graphics primitives such as lines, arcs, and symbols from previously defined symbol sets. In addition to general graphics functions, two distinct sub-groups of functions can be identified:
  • Graphics segment functions: used for defining segments and handling their attributes.

  • Interactive graphics functions: used for obtaining input from the operator by means of a logical input device.

• High-performance alphanumeric functions: used for defining, modifying, and deleting alphanumeric fields by means of field-lists. They are intended for use by applications that require minimal instruction path length within GDDM.

• Image functions: used for controlling the capture, transformation, and display of image data. These include two sub-groups of functions:
  • Image management functions
  • Image presentation functions

• Mapped alphanumeric functions: used for controlling the input and output of data, using maps that have been created with GDDM Interactive Map Definition.

• Operator window functions: used for controlling operator windows, which are rectangular subdivisions of a display device screen that have a different virtual device appearing in each. Operator windows allow more than one GDDM application to be run on the screen while under the control of a task manager, or one application to run a number of virtual devices sharing the same screen.

• Page functions: used for creating and deleting pages. A page is a rectangular area displayed on a device. The page functions determine how much of the page is displayed.

• Partition functions: used for creating and controlling real and emulated partitions. Several alternative logical screens, called partition sets, can be created on a device, but only one partition set may be shown at one time. Belonging to each partition set are one or more partitions that are rectangular subdivisions of the display area.
  Partitions are logical subdivisions of the screen. They can be used by applications for 'pop up' windows and similar constructs.

• Procedural alphanumeric functions: used for defining, modifying, and deleting alphanumeric fields and their attributes.

• Symbol set functions: used for passing symbol sets to and from files, the application program, GDDM storage, and the display device.

• Utility functions: used for calling GDDM utility programs from within application programs.

   Notes: