Equivalence only in one direction (Was: New Internet Draft on registering IDNs

[Stephane Bortzmeyer <bortzmeyer@xxxxxx>]

On Wed, Apr 02, 2003 at 06:35:40PM -0500,
 Martin Duerst <duerst@xxxxxx> wrote 
 a message of 690 lines which said:

> If there are two equivalent characters, and I as a registry want
> to allow a registrant to use either of these when registering,
> do I need two entries in the table?

This issue is not really clear to me in the current draft. But see
below.
 
> what about tables that don't have the same base character twice,
> but may map to the same character? E.g.:
> 
> U+00E8|U+0065
> U+00E9|U+0065

This is a special case of a more general issue, which is not clearly
stated in the current draft: equivalence goes from the Left Hand Side
to the Right Hand Side but not the reverse.

An example in French:

# Ligature oe
U+0153|U+006FU+0065

Every occurrence of <U+0153> is equivalent to the string "oe" but the
reverse is not true.

I suggest to clarify the draft in that respect (no, no actual
suggestion yet).