1. Transaction WE02 / BD87, Table EDIDC, EDI*
2. The functional module convert the logical file, which you created in the transaction FILE, in the physical file. In the FILE you can create logical file and logical path with variables, parameters, separated by operation systems. The file_get_name you can give the filename and you get the whole path (incl. filename) back. Then you use the generate path for "OPEN DATASET...".