Re: Syntax

On Mon, Jan 08, 2007 at 10:31:14AM +0100,
 Julian Reschke <julian.reschke@gmx.de> wrote 
 a message of 48 lines which said:

> Choosing characters for identifiers: again, just borrow from
> somewhere else, such as <http://www.w3.org/TR/REC-xml/#NT-Name>).

Did anyone already tried to convert it in ABNF? The production
BaseChar in the XML standard is a bit frightening and may exercice the
limits of some programs. Implementation reports are welcome.

Otherwise, what do you think of the solution used in RFC 4646?

   ASCCHAR    = %x21-25 / %x27-7E / UNICHAR ; Note: AMPERSAND is %x26
   UNICHAR    = "&#x" 2*6HEXDIG ";"

   Characters from outside the US-ASCII [ISO646] repertoire, as well as
   the AMPERSAND character ("&", %x26) when it occurs in a field-body,
   are represented by a "Numeric Character Reference" using hexadecimal
   notation in the style used by [XML10] (see
   <http://www.w3.org/TR/REC-xml/#dt-charref>).  This consists of the
   sequence "&#x" (%x26.23.78) followed by a hexadecimal representation
   of the character's code point in [ISO10646] followed by a closing
   semicolon (%x3B).  For example, the EURO SIGN, U+20AC, would be
   represented by the sequence "&#x20AC;".  Note that the hexadecimal
   notation MAY have between two and six digits.

> I think inventing a new format, but not taking I18N is very hard to
> defend. As far as I can tell, there's no real chance to get it
> published.

Hmmm, how many IETF formats are in Unicode? (Apart from those based
only on XML, like Atom in RFC 4287.) ABNF is not, for instance (right,
it is not a few format, the RFC is recent but it derives from an older
format.)

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