offset backwards?

[Ben Rubinstein]

This seems so simple that I feel sure it must be in transcript, given how
much else is - but I can't find it.

Is there a way to make offset (and the related functions) search backwards?
IE if I want to find the first occurence of "fred" in a string t, starting
after y, I can do
    offset("fred", t, y)

but if I want to find the last occurence of "fred" before y...?

Of course there are several ways I can code this - but I wonder whether
there's a syntax I've missed to make a single function call?

TIA
 
  Ben Rubinstein               |  Email: benr_mc at cogapp.com
  Cognitive Applications Ltd   |  Phone: +44 (0)1273-821600
  http://www.cogapp.com        |  Fax  : +44 (0)1273-728866