Do you mean something like a corner point of a curve, like doing the corner of a rectangle?

If so, then this feature is available - what you do is select the curve, then run fillet, and some selectable points will appear at all the corners on the curve. Select the ones that you want to round, and then you can enter a radius.

Fillet works in different ways depending on what is selected when you run it. If you have a single curve selected, it will allow you to round the corner points of that curve. If you select 2 curves it will extend them and make a rounded arc between them. If you have edges or solid objects selected then it will fillet the edges of the solid.

Please let me know if that wasn't what you were asking, or if you need any more details.

- Michael