Parameters: what do some fields mean

[Karol-Or]

There is the nominal value and the model value, which are always the same, even when i insert a formula.

I know, from the help, what they mean.

My question is why do i need both? are there situations where the formula result doesn't match the model value=the actual size of the param'?

[JDMather]

Try experimenting with Tolerances (Tools>Document Settings>Tolerances tab).
And setting a dimension at upper or lower tolerance.

[Karol-Or]

i set tolerance to 0.3 and precision to 0.1

I set, for two parameters, lower and upper tolerance, but i still see the nominal and the model values are equal: 20.0000

[Karol-Or]

I don't understand the logic behind tolerances and precision.

I have set tolerances, as in the picture, and the diameter parameter of size 20 became 20.3. why?

How do tolerances work, how are they applied

[Karol-Or]

I understood that since there is a global precision of 3 places, then the tolerance for 3 places is taken.

But where do i set this document setting of precision?

I did it with a right clik on a dimension, but, on the tools menu, document settings it isn't