Whilst browsing I found this and wondered what you meant by "S" designations. I saw what you meant once I opened the topic.
I was, of course, hurt by the fact that you don't have S-6 represented. Just remember, the three pillars of a functioning unit are to shoot, move, and communicate! Can't do much of the first two without the third!! 
Something else one might hear is "G" sections. These are for Division sized units and up (commanded by a general [thus "G"]). I work in the G-6 (communications) section for II MEF.
Something that is a little more recent in nature (I believe) is the "J" designator. They correspond to the meanings of the S and G sections, but are the designations for joint commands (composed of individuals from multiple service branches.)