Thanks for the pointer. Actually RFC6052 just refers to RFC4291 from 2006 in this case. And that simply calls it an alternative representation. Edit: RFC1884 f

Thanks for the pointer. Actually RFC6052 just refers to RFC4291 from 2006 in this case. And that simply calls it an alternative representation. Edit: RFC1884 from 1995 already had it, nothing has changed in that aspect.