ASTHELP has been implemented on top of the Starlink portable help system (SUN124). It is invoked via a FORTRAN programme which calls the Starlink HELP subroutines. As well as the normal hierarchical structure, facilities have been added which allow a hypertext-like feel to be included. This is achieved by having a separate index file which associates keywords with the path to a help topic. These keywords are invoked from within the ASTHELP session using the syntax described in the Using_ASTHELP section of help. At present this index file (AST_ROOT:[HELP]ASTHELP.INDEX) is a simple text file and keywords are located by a linear search. If it grows to the point where this becomes too slow, then we can implement it using direct access files and binary searching. With this in mind new entries should be placed in alphabetic order. Use upper case for command names and lower case for other things. To indicate to users of ASTHELP what keywords are available, they can be highlighted where they occur in the text by enclosing them as follows: -<keyword>- . The ASTHELP programme replaces the -< >- by ANSI escape sequences.
The full help text is to be found in ASTHELP.HLP (we may want to break this down into smaller files some time) and the command file, REPHELP in the same directory will compile this into the help library, ASTHELP.SHL (this takes some time!).
The full list of files associated with ASTHELP are:
AST_ROOT:[HELP] ASTHELP.HLP help text
ASTHELP.SHL help library
ASTHELP.INDEX index file
REPHELP.COM builds library
ASTHELP.EXE ASTHELP programme
ASTHELP.FOR source for above
ASTHELP.COM build programme