I've seen a couple of incidences now of modelers referring to S2F slats. The S2F had a fixed slot in the leading edge ahead of the feel ailerons. Kinetic molded this section of the leading edge separately, presumably because of molding problems with providing a good slot but possibly because they also thought this was a slat. I don't know what their instructions show. I've added some pictures of the slot to the end of my S2F blog entry. Click HERE.
Fotios Rouch has an excellent build article on Cybermodeler. Click HERE