Rotating Sectors permanently rotate around a pivot point. They are used for most anything... gears, doors, fans, lights, etc.

Create the sector which you want to rotate around a pivot point. Raise or lower the floor/ceiling to the desired height. Press R on the floor or ceiling if you want them to rotate with the sector. Place the following sprites within the sector: S[Channel,0] (M[AudibleRadius,AmbientSound], Speed[0,Speed]). For AudibleRadius, 1024 is equal to the largest grid square. Place an S[Channel,1] somewhere in the map (usually in the middle of the sector to be rotated). The S[Channel,1] will be the pivot point for the rotation. The angle of the S[Channel,0] determines the type of rotation. If it is angled down, only the sector will be rotated around the pivot point (definitely recommended). If it is angled up, the sector and the S[Channel,0] will be rotated around the pivot point (the S[Channel,0] acts as a sort of secondary pivot point). The angle of the S[Channel,1] determines the direction of the rotation. If it is angled down, the rotation will be clockwise. If it is angled up, the rotation will be anticlockwise.

Note: Rotating Sectors can only carry 'active' sprites (and of course the 10 intangible special sprites) without causing issues, and only if the floor's relative alignment is set (with the R key). However, they can also carry 'inactive' sprites so long as the sprites are situated directly on the sector's pivot point.