Re: [netmod] Alexey Melnikov's Discuss on draft-ietf-netmod-module-tags-07: (with DISCUSS)

[Randy Presuhn <[e-mail]>]

Hi -

On 2/14/2020 3:21 AM, Christian Hopps wrote:
> How about I add this to the description of "typedef tag" in the module:
>
>         description
>           "A tag is a type 'string' value that does not include carriage
>            return, newline or tab characters. It SHOULD begin with a
>            registered prefix; however, tags without a registered prefix
> -         SHOULD NOT be treated as invalid.";
> +         SHOULD NOT be treated as invalid. For the purposes of comparison
> +         non-ascii strings should use 'NFC' (RFC5198) normalization";
>       }
>

There are other considerations beyond normalization form.
For the tip of the iceberg, see the definition of SnmpAdminString
in RFC 3411, or the "SHOULD be avoided" stuff in RFC 5198.

For things like tags where one would like to minimize accidental
visual punning, I'd suggest NFKC should probably be given some
consideration.   Excellent presentation of the issues is
available at https://unicode.org/reports/tr15/

That said, these are issues that were raised in the earliest days of 
Netmod /
Netconf, and no one should be surprised that they haven't gone away by
themselves.  So I find my self in ironic agreement with Andy that it doesn't
make sense to wait for / impose a global solution, because there's plenty
of evidence that having all sorts of ill-defined cases of questionable
interoperability in theory hasn't been sufficient to prevent adoption of
the technology.

Randy