> I have a need to pass an additional Where statement element on the fly
> into a stored procedure, this wherestatement1 parameter will need to
> contain p.area in ('AAA','BBB','CCC') ;

You can use something like
WHERE ',' || 'AAA,BBB,CCC' || ',' LIKE '%,' || p.area || ',%'
or similar using CONTAINING if you want case insensitivity.

Ivan
http://www.volny.cz/iprenosil/interbase/