Additional thoughts on TRANSITIONAL

[Erik van der Poel]

Here is another proposal that is dead simple, yet allows
implementations to take advantage of a machine-readable file, and does
not involve "flag days" (dates at which we change something).

Instead of having a machine-readable file at each host, we have two
global files at iana.org. One file is similar to Patrik's table with
entries like:

00DF       ; DISALLOWED  # LATIN SMALL LETTER SHARP S
03C2       ; DISALLOWED  # GREEK SMALL LETTER FINAL SIGMA
200C       ; DISALLOWED  # ZERO WIDTH NON-JOINER
200D       ; DISALLOWED  # ZERO WIDTH JOINER

There is no new value called TRANSITIONAL. The infamous 4 characters
(above) start with the value DISALLOWED. Later, we change them to
PVALID (or CONTEXTJ for 200C/200D). We encourage ICANN to redelegate
TLDs the registries of which flout our rules.

The other file is for global mappings. Not language-specific mappings.
The format might be similar to RFC 3454's:

0041; 0061; Case map
00AD; ; Map to nothing

The absence of a character from this file means that there is no
mapping for that character. It maps to itself. The infamous 4
characters would not be in this file. In other words, their mappings
are removed, and new clients must stop mapping them. We encourage IANA
to set up a Hall of Shame, with a list of clients that flout our
rules.

Clients are permitted to check these machine-readable files once a
week, not at a fixed time on a fixed day of the week. Implementers are
not required to have their clients automatically check the files. They
may check them manually, and adjust their implementations as soon as
they can.

Voila. Dead simple. Machine-readable files. No flag day.

However, I would encourage .de and .at registry folks to take a closer
look at the .gr registry's claims that DNAME is not good enough for
email, etc. If DNAME is not changed to include the root of the subtree
or if no new xNAME is defined for that purpose, we may decide to keep
Eszett DISALLOWED and add a mapping to ss.

Most of the IDNAbis drafts can be published unchanged. We'd have to
change Patrik's draft for the infamous 4 characters. We might want to
drop the mappings draft for now.

Erik