By Isoparam

This option is useful when a surface need to by split in a given isoparametric curve. This operation may be used to separate surfaces with extreme curvatures in different parts. Tip u or v to change between the two parametric dimensions of the surface. Then, the point is specified as a parametric coordinate (between 0 and 1), and the pick mouse functions may be useful to split the surface close to any desired point.

One or multiple parametric divisions may be inserted in the command line, all of them corresponding to the selected U or V dimension.

To select the divisions points with the pick mouse functions, two different modes may be used:

Use the left mouse button to set an unique division coordinate. The previous values are removed and just the last one is considered.
Use the right mouse button to add the last coordinate to the already existing values.

Confirm the selected divisions by pressing Enter key in the command line.