Well-formed and valid

Sun Jan 9 04:04:31 GMT 2000

> Wrong.  A document type needs to conform to the specification that
> defines it: the specification

Of course David is quite right! I should have said that a document must
conform to a schema, and that a schema can be a DTD, or a 'schema' or a
narative description, etc. ...

Frank
----- Original Message -----
From: David Megginson <david at megginson.com>
To: xml-dev <xml-dev at ic.ac.uk>
Sent: Saturday, January 08, 2000 9:37 AM
Subject: Re: Well-formed and valid

> "Frank Boumphrey" <bckman at ix.netcom.com> writes:
>
> > > james anderson <James.Anderson at mecomnet.de> writes:
> > >
> > > > > ... it is possible to have a document that is well-formed but
> > > > > not valid XML 1.0, but still conforms to Namespaces, RDF, or XLink
> > > > > (though not XHTML, which requires validity for strict
conformance).
> >
> > Well XHTML is no different from any other _document type_.  A document
type
> > such as docbook or XHTML must conform to a DTD or it would not be a
document
> > type!
>
> Wrong.  A document type needs to conform to the specification that
> defines it: the specification may or may not include a DTD, and may or
> may not require the DTD to be used, but the DTD is at best an optional
> (if extremely useful) part of a document type specification.
>
> Here's an example of a document type whose specification does not
> include a DTD:
>
>   Memo Document Type
>   ------------------
>
>   Every memo document consists of a root element named "memo"
>   with two element children: "number" and "body", optionally separated
>   by whitespace.  The contents of the "number" element shall be a
>   number between 1 and 99,999, assigned sequentially; the contents of
>   the "body" element shall be text containing a minimum of one and a
>   maximum of three sentences, using UK orthography.
>
> Here's a document conforming to that document type:
>
>   <?xml version="1.0"?>
>
>   <memo>
>    <number>2,126</number>
>    <body>Look, mum, no DTD!</body>
>   </memo>
>
> Now, I could have written a DTD and required its use as *part* of the
> document type specification:
>
>   <!ELEMENT memo (number, body)>
>   <!ELEMENT number (#PCDATA)>
>   <!ELEMENT body (#PCDATA)>
>
> However, it would be trivially easy to write documents that conform to
> the DTD but not to the document type:
>
>   <?xml version="1.0"?>
>
>   <!DOCTYPE memo SYSTEM "memo.dtd">
>
>   <memo>
>    <number>Let me not to the marriage of true minds</number>
>    <body>123</body>
>   </memo>
>
>
>
> All the best,
>
>
> David
>
> --
> David Megginson                 david at megginson.com
>            http://www.megginson.com/
>
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