Adding the DTD to Our ML
April 12, 1999
Now that we have at least an initial DTD, we can associate it
with our XML document. When any
validating XML parser,
including the one in IE5, reads the document,
it will first parse the DTD and then, if the DTD is syntactically
correct, will
continue parsing the XML document.
Let's change collection1.xml so that it references
the local DTD that we generated in the previous section.
Change the opening processing instruction, remembering
that XML is case sensitive, so be sure to use exactly the
uppercase and lowercase characters shown below. Change:
<?xml version="1.0" standalone="yes" ?>
to
<?xml version="1.0" standalone="no" ?>
<!DOCTYPE Collection SYSTEM "collection1.dtd">
The above document prolog (as it is called) indicates
that this XML document requires another document (the DTD) to
define it. The DOCTYPE "Collection"
by convention matches the root level element of our document
viewed as a tree. The word "SYSTEM" implies that
the DTD which follows is a local file. Finally, the
path to the DTD relative to the XML document is given. If you
did not save the generated DTD in the same directory as the XML
document, you will need to adjust this path, or simply co-locate
the DTD and XML files.
If, however, we wanted to reference a public DTD located on a
web server, we would need to use a different DOCTYPE
declaration with a PUBLIC qualifier, the name of the language,
and the URL of the DTD, along with the same processing
instruction:
<?xml version="1.0" standalone="no" ?>
<!DOCTYPE Collection PUBLIC
"-//WDVL//Collection Markup Language//EN"
"http://wdvl.Internet.com/Authoring/Languages/
XML/Tutorials/DoingIt/Examples/collection1.dtd">
The above URL has been wrapped simply to make this page more readable.
In practise, you should not split this URL or any string in XML.
You have already downloaded an example of each case:
Generating a DTD the Easy Way
Doing It With XML, Part 1
Viewing It With IE5, Take 2
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