These are the detachSurface options. The options appear in the Attribute Editor.
These are the options in the Detach Surface History section.
You can enter a parameter value to change where the detachment occurs.
In the following figure, a V isoparm is selected, moved, then detached twice. The first detachment moves the seam of the cone, which is periodic in V.
If you change the parameter value, the detachment area is increased or decreased. In the following example, the parameter value is increased to 1.5.
To change the detach direction, select U from the Direction pop-up menu to detach the isoparm from a parameter value of 1.5 in the U direction.
You can edit the area of detachment with the Show Manipulator Tool. Select the detached curve and the detachSurface node in the Channel Box, then select the Show Manipulator Tool. If you drag the black manipulators, the area of detachment grows and shrinks accordingly.