Re: <?xml declaration

Chris Maden (crism@ora.com)
Mon, 15 Dec 1997 10:47:55 -0500


[Richard Light]
> I notice that the current draft has switched the case of the XML
> declaration and its arguments to lower case:
>
> <?xml version="1.0" encoding="UTF-8"?>
>
> Now that case is significant, this presumably matters.

Absolutely. Note the disappearance of the "match/exactly match"
dichotomy from the terminology section of the specification; *all*
matches must be exact.

> Is there a particular reason for this?

It was a posted WG decision to use lower-case for all possible
keywords.

> Other PIs will have a PItarget where 'xml' sits, and this isn't
> constrained to be any particular case.

Which ones? The WG-produced specifications will use lower-case, and
other applications are forbidden from using [Xx][Mm][Ll] per the prose
in the section on names.

> Wouldn't it be kinder to make it '<?' ('XML'|'xml') ... ?!

Not really. It was introduce an instance of case-insensitivity into
an otherwise completely case-sensitive specification, making education
more difficult.

> (The DTD declarations (<!ELEMENT, etc.) remain in upper case,
> presumably for compatibility with what SGML systems produce.)

Not for compatibility - it's required by ISO 8879. The NAMECASE
GENERAL NO parameter in the SGML declaration only affects processing
of the DTD and document instance; keywords declared in the declaration
itself are still folded to upper case. This means that any such
keywords (like ELEMENT, DOCTYPE, ATTLIST, NOTATION) must be uppercase.

-Chris

-- 
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"<URL>http://www.oreilly.com/people/staff/crism/ <TEL>+1.617.499.7487
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