[Therion] Question about "grid" command

Good morning, while debugging https://github.com/hbeni/therionsurface2survex/issues/1 i stumbled upon a format question i did not give tought until yesterday. With the "grid" command you specify coordinate origin and size of a surface grid: grid <origin x> <origin y> <x spacing> <y spacing> <x count> <y count> Until now i assumed that: a) these data has to be all positive. But i'm not sure... origin may surely get negative (like in wgs89 and for example western and southern of the 0-meridian/equator) And also stepsize - might it get negative too (esp. with flipped grids maybe)? b) the spacing might only be integer numbers, not floats Is this true? I just got an example with not-round stepsize.