This does not seem to work as I expected.

I have a tib_query with 2 calc fields, which are set up in program.
I have an on_calculate field routine which says
if (AField.fieldname = 'avail') then do somthing special.......

and this is fine the first time I open the query.

I later say 'invalidate calculated fields' expecting this to be met
again but no!

on inspection the on_calculate_field routine is met again but
the 'afield' has no name the two fields seem to have field no -1 and
-2 but I can't see a fieldname anywhere.

Should I have used a different property of Afield rather than its
fieldname ?