To show possession, add an apostrophe and an s to singular words or abbreviations:
DAS promulgates the state's administrative rules.
You can find all of 2017's legislative measures online.
SEIU's negotiators met with the DAS labor group.
To possessive singular nouns ending in s, add 's:
The hostess's invitation arrived late.
The witness's answer was barely audible.
To possessive plural nouns, and to the term "DAS," add only an apostrophe:
DAS' teams worked hard on the project.
All the teams' efforts resulted in success.
Be careful not to confuse possessive adjectives, which do not take apostrophes, with contractions, which do:
PEBB revised its administrative rules.
It's on the web.
Omit the apostrophe from plurals that are not possessive:
Things changed in the 1990s.
All OARs are on the web.