> On 25 Feb 2021, at 17:59, Dave Crocker <dcrocker@xxxxxxxxx> wrote: > > Sorry, no. Copying specification details invites divergence. And the style of inclusion by reference done in this specification is not that unusual. Experience with Unicode have shown that is exactly what we need. What I am after is not *copying* from UT#51. I want the subset of what is in UT#51 that suits this spec be expressed in ABNF like the rest of the specification. This to ensure interoperability to the degree IETF feel comfortable with. My point is that IETF will not be able to make that determination unless the specification of what is valid and not is expressed in the way IETF can evaluate it. I specifically think about sequences including ZWJ, different directionality in contexts of multiple emoji etc. This is also why I suggest starting with a very limited set of code points and then later opening up. So not the same mistake is made as we made with domain names, which are as you say a different animal. But where issues with sequences still exists. Patrik -- last-call mailing list last-call@xxxxxxxx https://www.ietf.org/mailman/listinfo/last-call
