Edit Curves > Modify Curves > Unlock
Length
When you select Edit Curves > Modify Curves > Unlock Length, the selected curve (or selected CVs) will no longer maintain a constant hull length. If you then modify the curve, for example, by moving a CV, the curve’s hull length will not remain constant (and only the CV you move will actually move).
When you select Edit Curves > Modify Curves > Unlock Length, the curveShape’s Lock Length attribute is turned off.