Spine is a curve which profile will be positioned to it perpendicularly. If you select nothing for spine, guide curve accepted as spine.
Surfaces can be limited by selecting Rel1 and Rel2. (select points for this)
Angular correction and Deviation is used with a tolerance value to deviate and deflect from curves to create a surface with small errors.
Answered with a tutorial: https://grabcad.com/tutorials/optional-elements-in-sweep-command-of-surface-design-catia-v5-r21--2
Attachmentssweep optional pro.CATPart, 137 KB