I have a rating on CATIA V5R18 on which I want (it's rather my customer who wants it, but personally the current state of affairs suits me) a different precision between the nominal and the tolerance. I want a nominal rating of 5.95 and a tolerance of +0.2/-0.3. But I can't, is it possible? If so, how? If not... well too bad
Personally I don't have any problems. You set the dimension and then right-click on the dimension => properties. In the tolerance tab you choose a tolerance format from the "main value" list (here TOL_NUM2). Then simply enter the values with the desired precision. See the attached view.
I also did the test, you can even have a different precision in + and -(e.g. +0.25/-0.3).