Some PCB packages allow the user to manually add/modify Tracks,
like pcbnew does and then by connectivity they become either a
new net or part of an existing one. The netlist export would be
an additional DRC method to verify the user didn't break the golden
netlist input.
A netlist compare utility would be needed to compare the export
to the golden input. Manual trace modifications in general are
risky and should be avoided IMHO.
My observation is that pcbnew doesn't tag which net each track
corresponds to.
