Comment 8 for bug 1709342

I agree with Mc.

If we now add feet and meters it's only a matter of time until somebody wants to use miles or lightyears.

Unfortunately it seems we do not have any documentation on this (the closest is probably [1] which does not discuss units.xml, though).

[1] http://wiki.inkscape.org/wiki/index.php/Units_In_Inkscape