Subsection is one word an their official abbreviation would be A.S. (of the S.S.S.). I just think people find ASS funny and nobody really cares is a little comedic influence is injected here and there by the community.
Yeah, ASS fits nicely with Steel Phallus, and the rumoured proclivities of certain mythical Hellenic personalities.
Nonono. Since it is Assault Subsection of the SSS, we take first letters of all and end up with ASS! :D Multilayer it!