Row grammar
All 14 scenarios hold
These rules cover how one line divides into fields. They apply before the parser reads a field as a value.
Each Row below is parsed as the only data row under a one-column header. Fields shows the captured field list, printed back out. Fields is text rather than a list column because a list cannot hold a null element: writing [a, , c] is itself a parse error. A null field is what several of these rules are about.