DFU
From MidrangeWiki
DFU = Data File Utility.
We can use it to create a format or simplistic "program" that will let us update a file one record at a time, or with option 5 from STRDFU, we specify the physical or logical file and member (or *FIRST) then the 400 will setup a dummy set of DFU specifications on the fly, to let us update that file.
The file layout has to exist before we can access it vie DFU, while we can use DFU to add records.
