Internationalized Domain Names in Applications (IDNA): Registry Restrictions and Recommendations
draft-klensin-idna-rfc5891bis-06

[I thought I would skip these, but since this will likely need another IETF Last Call,
maybe you want to pick some of these suggestions up as well.]

This document uses RFC2119 keywords, but does not contain the recommended
RFC8174 boilerplate. (It contains some text with a similar beginning.)

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All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools, so there will likely be some false positives. There is no need
to let me know what you did with these suggestions.

Section 4, paragraph 7, nit:
-    operate to produce revenue about actual costs, are sufficiently
-                                  ^^
+    operate to produce revenue above actual costs, are sufficiently
+                                  ^^

Section 2, paragraph 3, nit:
>  already registered in the zone, so as to avoid homograph attacks [Gabrilovic
>                                  ^^^^^^^^
'So as to' expresses purpose and is used in formal texts. Consider using "to"

Section 2, paragraph 4, nit:
> nion of the needs for all zones as well as to the desires of the most permiss
>                                 ^^^^^^^^^^
Probable usage error. Use "and" after 'both'.

Section 3, paragraph 7, nit:
> olicy, with the expectation that some of the code points in the MSR would not
>                                  ^^^^^^^^^^^^^^^^^^
If the text is a generality, 'of the' is not necessary.

Section 3, paragraph 9, nit:
> ts they understand. In this, some of the other recommendations, such as the I
>                              ^^^^^^^^^^^
If the text is a generality, 'of the' is not necessary.

Section 4, paragraph 5, nit:
> t might be considered clever, much less ones that are hard to type, render, o
>                                    ^^^^
Did you mean "fewer"? The noun ones is countable.

Section 5.1, paragraph 2, nit:
>  In retrospect and contrary to some of the suggestions in the errata, that va
>                                ^^^^^^^^^^^
If the text is a generality, 'of the' is not necessary.

Section 5.1, paragraph 2, nit:
> vely with Unicode code points. Consequently the relevant material in RFC 5890
>                                ^^^^^^^^^^^^
Did you forget a comma after a conjunctive/linking adverb?

Section 5.1, paragraph 7, nit:
>  UTF-32), U-labels that obey all of the relevant symmetry (and other) constra
>                              ^^^^^^^^^^
Consider using "all the".

(1) Labeling one category of zones as "for-profit" gives me pause because a number of such zones are operated by not-for-profit entities, and retaining that status is quite important for both them and the Internet (e.g., .org, which is obviously significant for the IETF). I think the distinction being made is not whether the zone is run for profit, but whether it is commercial -- that is, whether domain names in the zone are bought and sold. 

(2) Section 4 says:

"While the IETF rarely gives advice to those who choose to violate
   IETF Standards, some advice to zones in the second category above may
   be in order.  That advice is that significant conservatism in what is
   allowed to be registered, even for reservation purposes, and even
   more conservatism about what labels are actually entered into zones
   and delegated, is the best option for the Internet and its users."

I don't see how we can have this formulation in a consensus IETF document. Either we are giving the advice to the specific audience, in which we should give it in a straightforward manner, or we are not giving the advice, in which case we should not have this text in the document. I think a better approach would be to re-formulate the whole paragraph in which this text is embedded to explain what the best practices are as far as conservatism for registries and registrars of any type.