Thanks much for the explanation, regarding the differences between these agencies. My first dive course (NAUI/YMCA) in the 60s taught decompression as part of the course. I can see the pros and cons as to why decompression diving is left as a separate certification. My personal experience with French divers has been great. They are very safety conscious and knowledgeable. I had some miscommunication with hand signals regarding bar pressure, that's about it.