Looping record to single fields

Hi everyone, 

today I ran into a problem that gives me quite a headache, even after hours over hours of experimenting and googling. 

Following scenario: 

Our business partner is sending invoices in EDIFACT D97A INVOIC format. 

In the RFF segment there are 3 possible values sent to us. 

These values are to be mapped in single fields in our destination schema. 

I know how to do this the other way around ( collecting values from single fields and put them into a repeating record) with table looping fungicide, I understood conditional looping, too. 

But this does not appear to be applicable here ( or I just don’t get the logic behind it). 

Does anyone know how to do this with functoids? 

Or am I forced to use xslt? 

Many thanks, 

David