DOCTYPE and URI

[DuCharme, Robert]

>When specifying the URI for an external DTD in the DOCTYPE declaration, is
>it generally accepted that a network-accessible document should be
>specified, or a local one?  I often see examples where the URI is
http://...
><http://...> , but I find it hard to imagine that *every time* a particular
>XML file is parsed by a validating parser, the DTD is downloaded from some
>remote web server.  The XML spec does not seem to talk about this, but is
>there some search algorithm that allows a remote URI to be overridden by a
>local file, if it exists?

As far as I know, relative URIs of the form 

  <!DOCTYPE foo SYSTEM "foo.dtd">

(or some other relative path like "../dtds/foo.dtd") is more common than
using remote DTDs, although this may be changing. The beauty of allowing
relative URIs is that it makes it all backward-compatible with the SGML way,
in which URIs were not an issue. 
In XML terms, the above example points to a relative URI that is in the same
directory as the document, so if the document is local, the DTD is assumed
to be as well. 

Bob DuCharme       www.snee.com/bob       <bob@  
snee.com>  see www.snee.com/bob/xmlann for "XML:
The Annotated Specification" from Prentice Hall.

xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev at ic.ac.uk
Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1
To (un)subscribe, mailto:majordomo at ic.ac.uk the following message;
(un)subscribe xml-dev
To subscribe to the digests, mailto:majordomo at ic.ac.uk the following message;
subscribe xml-dev-digest
List coordinator, Henry Rzepa (mailto:rzepa at ic.ac.uk)