There are a few things to keep in mind when working with curves.
Using Weight Maps on Curves
You can apply a weight map on a curve, but you cannot display it or paint on it. You can only use the constant or gradient
base map generated by the WeightMapOp operator, or set weights using an ICE tree.
Displaying Information on Curves
Press Shift+Enter or choose to get useful information about the selected curve object, including its length in Softimage units.
Info Selection