Comments that don't affect the normative content:
No need for comma (and attendant typo) in "unassigned , or unnecessary".
Should SG16 be still listed as part of the audience?
This sentence is ambiguous:
This proposal does not address some potential security concerns, so called homoglyph attacks, where letters that appear the same may be treated as distinct.
Is the intended scope of the "potential security concerns" coincident with "homoglyph attacks"?
Replace:
Defending against such attacks is complex and evolving
with
Methods of defense against such attacks is complex and evolving
-- HT