Re: [precis] Ambiguity in specification of case mapping in RFC 7613 and draft-ietf-precis-nickname

[Tom Worster <[e-mail]>]

On 11/3/15, 8:42 AM, "John C Klensin" <[e-mail]> wrote:

--On Tuesday, November 03, 2015 08:16 -0500 Tom Worster
><[e-mail]> wrote:
>
>> The informative sentence in 2.1 Rule 3:
>> 
>>     "The primary result of doing so is that uppercase
>> characters are     mapped to lowercase characters."
>> 
>> is good but I think it's worth spending a few more words to
>> spell out that "primary" implies exceptions.
>> 
>>     "While the primary result is that uppercase characters are
>> mapped to     lowercase characters, there are exceptions."
>> 
>> It might nudge a few fore implementers to understand that
>> toLowerCase() isn't the right thing.
>
>But Tom, for many purposes, forms, and language-script
>combinations, toLowerCase() is _exactly_ the right thing.  For
>others, if one adopts the principle of doing no harm, whether
>toLowerCase() or toCaseFold() are likely to do less harm depends
>on some rather subtle issues including the perspective from
>which "harm" is viewed.
>
>I think one could more accurately restate your comment above as
>"... to understand that toLowerCase() is sometimes not the right
>thing and that sometimes toCaseFold() is sometimes not the right
>thing either.

You're quite right while my last sentence was not. Please humor me and
pretend I hadn't written it in that email.

Tom