What rules have been used for the current list of codepoints?

[Gervase Markham]

Erik van der Poel wrote:
> What do you suggest for the labels other than the TLD and 2LD? Do you
> suggest that the top-level registry adopt and enforce policies at all
> levels, including 3LD, 4LD and so on? And/or do you suggest that the
> user agent enforce some rules at those levels?

Of course, user agents should additionally restrict which characters are 
permitted globally. We currently have a blacklist (I think) of our own, 
but having a universally-agreed set is what this group is about, isn't it?

Gerv