Marking as won't fix, we're stuck between a rock and a hard place... Either:
1) We mark it as required (which is then wrong for sample importing)
2) We mark it as optional (which is then wrong for lines/list importing)
Given that we:
1) Document that it's required for lines/list format
2) Return an error to the user clearly indicating that it's required when not supplied
I think we're already handling this sensibly i.e. whatever way we do it, someone will disagree.
I'd say the real issue here, is probably that we lump lines/list and sample format into a single man page (which is valid) but means the documentation has to be slightly broader (ideally, we probably shouldn't have documented the sample importer in the first place).
Daniel Owen please let me know if you disagree with the above.