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The example application TSTHLP works in the simplest way possible. Most
real-life applications will be more sophisticated:
- The output routine HLP_OUTSUB used in
TSTHLP outputs lines of text to the terminal without
regard to screen management. The output routines of real
applications may count lines and issue a ``press return for more''
message after a certain number, then wait for a response before going
on; on appropriate terminals there may be screen erasures; and
so on.
- Some sort of ``abort'' feature is useful, to provide a
quick exit from the help session. On the VAX,
detection of <CTRL>/Z in the
application's input routine (by means of the END= feature
of the READ statement), followed by simulation of multiple
<CR> responses and ignoring of lines supplied to the output routine, is
one way to arrange this.
- In the VMS DCL command HELP, a "?" response requires no
<CR>, and it is possible an application may wish to provide this
feature. (The demonstration program TSTHLP does not.)

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HLP --- Interactive Help System
Starlink User Note 124
P. T. Wallace
13th June 1995
E-mail:ptw@star.rl.ac.uk