plural acronyms that end in S

[Sandi]

The acronym for California State System could be CSS. To make this acronym possessive would it be CSS's (since the final S stands for System, which would normally be followed by an 's) or CSS'?

Thanks

[teacherjulia]

It is a style issue, so you just need to keep it consistent.

If you would write "Kansas's laws" then write "CSS's business." If you would say "Kansas' laws" then write "Css' business."