The EDI BNF defintions do not seem to be correct for the WRK record (and possibly all other records)

[jasrys]

Given this definition:

The EDI BNF for WRK is:

The square bracket suggests that SPUs and SWRs are not required, enabling a situation where a WRK could be submitted without any writer or pub info which doesn't make a lot of sense

[jasrys]

There are cases where writers may not have publishers, so maybe it is actually optional. Leave it alone for now