Some very poor files do not specify the coordinates format.
In this case, the default is INCH,LZ that looks like the more usual.
From master branch, commit b1fd462
Routing mode starts by M15 (or G01, G02, G03) and ends by M16 or M17.
Accept now a end routing if a G00 (start move) G05 (switch to drill mode) or M30 (end of file) is encountered.
Previously, the M and G00, G01, G02 and G03 commands were read, but nothing was actually done.
The current support is a bit rough, but it allows reading some drill files with routing commands.
jean-pierre charras
Jon Evans