Almost any program that does any graphics requires the user to identify which graphics device is to be used. When the graphics package used by the program is GKS (SUN/83)—and for the majority of Starlink software it is, at least indirectly—graphics devices are identified by two integers, a ‘workstation type’ and a ‘connection identifier’. (‘Workstation’ is GKS terminology for a graphics device of any description and this is the sense in which it is used throughout this note.) No one can be expected to remember the workstation types of all the devices supported by Starlink (nearly 50 at present) so a library has been provided that translates ‘friendly’ and easy to remember names into their GKS equivalents.
Most high level graphics packages, such as SGS SUN/85) and PGPLOT SUN/15), call GNS to perform
the necessary name translation when a workstation is opened, so unless you are writing programs
that open GKS workstations directly (by calling
GOPWK), or need to make specialised device inquiries,
you will not need to call any GNS routines yourself.
The graphics workstation name service library provides three sorts of service to the users and writers of graphics subroutine libraries and applications programs:
GNS also provides support for the Image Display Interface (IDI—SUN/65) and the Applications Graphics Interface (AGI—SUN/48), but in both cases the use of GNS is internal to the librariy and so its presence is not normally apparent to the programmer.