Re: [idn] Editorial comments on stringprep

["Mark Davis" <mark@macchiato.com>]

> This passage describes an *internal process* only.  This has nothing
to
> do with the Unicode Consortium or Technical Committee preferring
> lowercase forms over uppercase for user-visible operations, and it
> definitely does *not* claim that mapping to lowercase is more
consistent
> or "better" than mapping to uppercase.  There is no explanation
given
> for the phrase "a single lowercase letter where possible" to explain
why
> lowercase was selected.  It appears to be an arbitrary choice.

The choice of whether to use upper or lower for folding was originally
somewhat arbitrary; either could have been chosen.* However, the
choice of lowercase was made for folding operations, and was
encapsulated into the case folding mappings in the UCD. This does not
indicate an fundamental sort of 'preference' by the consortium for
either case in general text processing, but for a folding operation
one must chose, and the choice needs to be stable.

*The main reason for choosing lowercase was that there are more
characters with lowercase-only than uppercase-only. These characters,
mostly IPA, are lowercase in form but have no corresponding uppercase
equivalent. Occasionally corresponding uppercase characters are
added -- when the character is added to the orthography of some
language and ceases to be only IPA (when this happens, it is typically
for an African language), and an uppercase is required.

Mark