No doubt it will be some mind blowing, world shattering rule.
Such as mirrors must be made of shatter proof plastic and not glass as it might break and leave sharp edges, therefore too dangerous.
Cynical?
Me?
------------- I started out with nothing and I've still got most of it left - Seasick Steve 2008
Frankly I wouldn't worry whether they conform to latest EU regulations. Considering how many caravanners tow without towing mirrors, I think there is a long way to go before you get stopped to check if they conform.
I saw a post on here a while ago about this and it was in the c.c. mag , something that towing mirrors had to conform to e.u. standard and the only ones which did were milenco but Ithink it was milenco themselves who brought the subject up in the first place