Olin Lathrop wrote:

>>>> All CAD where I've looked into this use an integer representation
>>>> that is a sub-multiple of both mm and mil.
>>
>> Can that work? What base unit would that be? I don't think such a
>> number exists.
> 
> It certainly exists and some CAD systems use exactly this method.  As
> someone else already pointed out, 100um is a sub-multiple of both a mm (10)
> and inch (254).  By factoring out the common 2, you get 200um as a base unit
> for both (1/5 mm and 1/127 inch).  You can keep scaling that down until you
> get the resolution you want.

Ok, yes of course :)  The original poster said (see above) "a sub-multiple
of both mm and mil". That would then have to be 200 nm.

This means that the system needs to use a metric unit as base unit. This
works. I'm just not sure that all systems use a metric base unit. The ones
who don't probably have more trouble.

Gerhard

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