1 INTRODUCTION

 1.1 Comparison with VMS Help
 1.2 Portability
 1.3 Package Contents

The Starlink HLP system is a set of subprograms and utilities which allows an application program to retrieve named items from a hierarchically-arranged library of text.

The facility is functionally very similar to the VAX/VMS Help system. The major differences are that the Starlink HLP system (i) is implemented in a portable way and is not tied to the VAX, and (ii) allows independent creation of multiple libraries which are bound together at run-time and appear to the user as a single “tree”. The system is written in a free-standing manner and does not call any other Starlink packages.

The present document will be of most interest to application programmers, though users of application packages which incorporate the HLP system may find Section 2 of some value. Section 5 is relevant only to those providing software support for the package, or others who are interested in the internals of the system.

1.1 Comparison with VMS Help

Readers already familiar with the VMS Help system may find it most convenient to begin by looking at how the Starlink HLP system differs. In the list, below, the most useful or significant features are described first, with less important differences later.

1.2 Portability

Although the Starlink HLP facility is functionally similar to the one provided with VAX/VMS, it is not tied to the VAX, makes no use of the VMS Librarian utility and Run-Time Library and does not depend (to any significant extent) on DEC Fortran extensions. Written almost entirely in ANSI-standard Fortran, the few unavoidable machine and operating system dependencies are isolated within a small number of routines which are supplied in different forms for different platforms. At present, VAX/VMS, Sun/SunOS, Sun/Solaris, DECstation/Utrix and DEC Alpha/OSF-1 variants are available (there is also a private PC/MS-Fortran version available from the author), plus functionally inferior but machine-independent variants.

The present document describes only the VAX and Unix versions. The VAX release contains also the PC versions. More information on portability issues can be found in Section 5.2.

1.3 Package Contents

The main components of the Starlink HLP system are as follows:

Other useful items include:

Also supplied, but of less interest, are: