To step back to the SPO paradigm, using EDITEUR as example.
base of editeur:message is edifact:message
extension of editeur:message is editeur:item.characteristic.coded
replacement of tred:item.characteristic.coded is editeur:item.characteristic.coded
codelist of editeur:item.characteristic.coded is editeur:7081
translation of editeur:7081:010 is Author Name
similar of editeur:7081:010 is uncl:7081:76
So RDF would allow translations between UN/EDIFACT and EDITEUR as it would allow a native use of EDITEUR messages. As similar SPO sentences can also be made about the ETIS extension, I hope RDF is well suited to describe UN/EDIFACT and its extension.