I think the true wording of the ICC should be :-
ICC - International Certificate of Competence for a skipper whilst skippering a ......@.....(name of country in which issued) registered vessel abroad in the limited International countries that accept it. The ICC is not valid for skippering any other vessel abroad not ........@....... registered, but may be accepted at the discretion of any charter company in a country signed up to UN resolution 40.
It would then be helpful for the relevant countries that have signed up to be listed.
I would also question the word International as although it is partly right it can be misleading, but this would be clarified by listing the 'International countries' signed up.
Anyway, thanks to everyone for all your input, I am sure that a lot of people have learnt a bit more about an ICC, I will leave it for the professional trainers among the forum to pass on any comments they feel necessary to the relevant authorities.