AF anyone can use HSE, if that is the bottle of use within that region even an American/Canadian etc. It only becomes an issue if you try to use an HSE in another country that has a different test system and you are NOT from the country where that test is the norm. If that doesn't explain it clear enough...
I am english so must use HSE within England nothing else.
When in the States or Canada I can use that HSE tank cos I am VISITING
I can also use a DOT, but only when I am in the country for who DOT is the test.
I cannot at any time use a DOT/or any other form of standard of test in the UK.......I admit it will cause problem if you follow it to the letter of the law 'cos it would mean I can't chrono any foriegn markers equipped with DOT/whatever bottles (so perhaps this is where the Mill annoucement came from?) but then that is semantics. (where the hell is Hotpoint when you need him)
Chunk may very well be from Ireland but is it N Ireland or Eire? if Eire then he may well be subject to a different standard to you and I