I have an odd situation that I am trying to figure out in the drafting standards.  I’m using SW13 SP4.

Looking at a drawing, our document property standards show that our units are three decimal places for basic unit length but our primary precision under dimensions are two decimal places.  When I create a dimension it shows, in the tolerance/precision section, that it is “.12 (document)”.

If I change the primary precision to four decimal places and create a new dimension it will show as “.1234 (document)” but the units remain at three places.  If I then change units to two decimal places and create a new dimension it will show as “.12 (document)” but the primary precision will also change to two decimal places.

So changing units changes primary precision but changing primary does not change units.  If I want them the same I should change units but if I want them different then I need to set units and then set primary precision.  Both change how it will dimension.

I guess my question is why?  Why do we have these two if they are basically the same thing?  What am I missing?  I thought that units would be modeling but primary precision would be drafting but then they should not tie together where changing units changes the drawing or primary precision.