DOCTYPE (was Re: Announcement: SAX 1998-01-12 Draft)

Peter Murray-Rust peter at
Wed Jan 14 01:05:13 GMT 1998

At 09:58 13/01/98 -0800, W. Eliot Kimber wrote:
> [PeterMR] > How do we determine the TYPE of a document?  There is no good
>> mechanism.
>Not true.  All that is necessary is to provide some way to point to a
>separate definition of the type.  The SGML architecture mechanism,
>defined in ISO/IEC 10744:1997 and implemented in the SP parsers (as well
>as in purpose-built code) provides just such a mechanism.  In December,
>James and I submitted for WG4 approval an enhancement to the formal
>mechanism that lets it be used with XML documents. See
>The idea is a simple one: you use a PI to associate a local name for the
>"type" and then use a URL or public identifier to point to the
>documentation and the DTD that defines the type.

Thanks. I wasn't aware of this. We need something like it.  It does, of
course, rely on building a significant registry for FPIs. As far as I
remember from previous discussions very FPIs are registered at present, and
the mechanism is not widely known. If this mechanism is to become popular
for XML - before the WWW gets swamped with untyped documents without
meaningful FPIs - there needs to be a lot of effort to publicise and
implement it.

>For example, ISOGEN has defined for its own use a base architecture from
>which a variety of specific document types can be derived.  I can invoke
>the use of this architecture like so:
><?XML 1.0 ?>
>  name="ISOBase" 
>  public-id="+//IDN ISOGEN Base Architecture//EN"
>  dtd-system-id=""

As I understand it, these PIs are *permitted* in XML (any PI is permitted)
but they are given no special importance and implementers are not required
to support them. So XML - as it stands today - has no mechanism for
requiring this to be implemented or interpreted.


Peter Murray-Rust, Director Virtual School of Molecular Sciences, domestic
net connection
VSMS, Virtual Hyperglossary

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