Doug Ewell dewell at
Wed Jan 31 15:35:08 CET 2007

Stephane Bortzmeyer <bortzmeyer at nic dot fr> wrote:

> From the ABNF Police Department:
> It does not matter since the hex digit is case-insensitive.
> RFC 4646 says:
>  UNICHAR    = "&#x" 2*6HEXDIG ";"
> and refers to RFC 4234 which says:
>         HEXDIG         =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
> (And strings in ABNF are case-insensitive)

To clarify my point, it does not matter whether the Registry uses 
uppercase or lowercase in hex escapes, but it would be gratuitously 
inconsistent to use uppercase in some places and lowercase in others for 
no apparent reason.

> As Frank Ellermann reported, the currently-discussed Internet-Draft 
> draft-klensin-unicode-escapes-01 may be relevant here. See 
> for instance (and if 
> you want to participate).

This is a topic that needs to be raised at the RFC 4646bis level.  RFC 
4645 and RFC 4645bis simply follow the rules set by the governing RFC.

My personal view on the \uXXXX syntax is that while it may (or may not) 
be better than what we have, it is not "better enough" to justify making 
a destabilizing change (since there would be no reason to support *both* 
escaping conventions), whereas supporting UTF-8 directly would be.

Doug Ewell  *  Fullerton, California, USA  *  RFC 4645  *  UTN #14

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