Thanks guys. I’ll check those out.
After going back to Casio’s website, I’m now looking at the Frogman
http://www.casio.com/news/content/E95D2549-CB7A-4A27-99C4-6D39A73E4AFB/
It seems they are making a distinction between 200M water resistant and ISO 200M wr. They say the Frogman is their only true 200M watch, and on the face it says "Divers 200m". Suggests to me this is better than their regular 200m.
Still studying.