From what I understand, a COA would most likely be used by a municipality like a FireDepartment or or City EMS division that would have their own program. The program would have standard Ops for training, maintenance, flight as well as documentation. If you are flying under that COA, which would have specific guidelines in the COA, you would not need to be Part 107? Someone please correct me if I am wrong. This was frequently used in the past to allow exception to fly at night for one example. We had one for our SnR group early on.