The trouble is that the "field language" does not have a construct that can
do that, which is why I made the other suggestions.
But if you can't use /any/ of those suggestions and you can't modify the
data source then you can't really solve the problem. There is one other
approach involving SQL (which can sometimes be used with a plain text data
source) but it also requires you to use VBA and I get the impression that
you are not allowed to do that.
Peter Jamieson