Hi Robert,
the list of function module to create the filename is customizable.
So, you could try to create a function module custom, that use the tables parameter as EDIDD (content of idoc) as the follow:
FUNCTION zz_idoc_input_name.
*"*"Lokale Schnittstelle:
*" IMPORTING
*" VALUE(DATATYPE) LIKE EDIPO-ACTRIG
*" VALUE(DIRECTORY) LIKE EDIPO-OUTPUTDIR
*" VALUE(FILENAME) LIKE EDIPO-OUTPUTFILE
*" VALUE(CONTROL) LIKE EDIDC STRUCTURE EDIDC
*" EXPORTING
*" VALUE(PATHNAME) LIKE EDI_PATH-PTHNAM
*" TABLES
*" IDOC_DATA STRUCTURE EDIDD
*"----------------------------------------------------------------------
And then read the idoc's data to complete the pathname.
Simon