Adopting ZWJ

[Karl Williamson]

On 06/07/2016 02:48 PM, Karl Williamson wrote:
> I heard that someone was considering adopting ZWJ.  They seemed to think
> that non-printables are not adoptable.  But I was unable to find a clear
> list of criteria.  The page that allows one to adopt said that it wasn't
> available, but that page really doesn't make it clear how one can test
> for this without actually doing the adoption.  (Since it doesn't
> actually ask for your credit card number on the initial page, one can
> back out before the final commitment, but that's not a very friendly
> interface)
>

After I wrote that, I found this that I previously overlooked

"You can’t sponsor candidate characters (those not yet released in a 
version of Unicode, such as the Emoji Candidates), nor certain 
characters such as invisible ones."

But why this rule.  Why should someone be forbidden to adopt ZWJ?