Just found I can do calculated polygon changes via OI

[unearthed]

Just drawing up a very irreguilar, undocumented house, and idly put a -Distance into the OI box, I didn't know this was possible - not a game change but undocumented as far I was concerned, not at all equal to Acad's version but better than nothing 

[Pat Stanford]

You can do math in pretty much any number field.

 

And not just math, but also unit conversion.

 

So if you have a field with a distance of 10 meters you could do something like:  10 + 6' and end up with the correct distance in meters from adding the 6 feet.

 

Add, subtract, multiply, divide.  Probably more.