There are Nine global parameters you can define in explicit presentation or even directly in the basic formula to make your curve easy to modify or animate. These parameters are available in explicit presentation to edit, entitled ‘Animation parameters’. The scheme above shows the parameters used in Ellipse formulas.

Note 1: these parameters are disabled until you define animation parameter from explicit presentation.   

Note 2:  all parameters are available in global scope with the same name.

Note 3:changing the parameter in modify panel will force the program to regenerate the mesh.

Note 4: you can animate these parameters like other parameters in 3ds MAX.