measure distance

I'm wondering if there's a way to set two points on a spline and then measure the distance between these two points, along the spline, not the minimum distance (which is what shows up automatically in the measurements bar). Any thoughts?

Hi, I'm trying to do some 'easy' calculations in a variable and found this odd. I'm using the Measure Distance custom feature to get a distance in the model. I left the default name #distance. I assign it to a new variable to see the value, works fine. I assign #distance*2 to a variable, still fine. I assign #distance+20…