I don't think this is possible, but what is possible is to have one
'master/main' powerpoint file that calls up all the others, returning to the
'master/main' show after hyperlinking to invididual shows.
Thanks TAJ. I though that what you say was the case. I am familiar with
the technique that you describe (I use it regularly) - and have now worked
out a variant of it that will suit my needs.