1 Introduction

This note describes the release on Starlink of the RAL/ICL GKS graphics package.

GKS has two major advantages over other graphics packages:

• It is an international standard and real portability of graphics software is now possible. An illustration of this is that the NCAR package—an extensive library of scientific graphics utilities produced by the National Center for Atmospheric Research in the USA—runs on the RAL/ICL GKS without any modification, despite the fact that it was developed using a completely independent GKS implementation.
• No other package provides the ability to write device independent graphics programs to the extent that GKS does. Only with GKS can you write a program that will run, and produce good pictures, on all devices supported by the implementation, including devices not supported at the time the program was written. Programs can nonetheless still fully exploit all the facilities offered by the hardware.

The RAL/ICL GKS implementation has several advantages of its own; it contains features which are not all found in any other single package:

• Area fill with several fill styles on all devices.
• Cell array supported on dot matrix printers.
• Multiple fonts.
• Selective clearing of display surface.