If you select only three curves, Maya will create a “three-sided” surface (see notes below).
If you turn on the Partial option to use a subsection of the curves, you can control which part of each curve Maya revolves by selecting the subcurve node in the channel box and editing the minValue and maxValue attributes. If you have the Show Manipulator tool selected, handles appear on the curves to allow you to drag the values.
Some of the curves may be reversed to make sure their start and end points match. The first curve you select is used for the surface U parameters.
If you select opposing pairs of curves in order (that is select the first curve, then select the curve on the opposite side, then the third curve, then the curve opposite it), you can determine which curves will control which parameters.
If the end points of two side curves do not meet exactly, a short straight line segment will result instead of a zero length line.