The XML Document Type Declaration (DTD)

As described in the January 2004 issue of CPU - Computer Power User magazine.

Examples

A) Downloadable ZIP File

• There are several examples here -- why not download the whole lot as a ZIP file -- jan04.zip -- and install them on your own machine?

B) The example XML documents

• data-1.xml -- The example document declaring a single internal entity named test with the value: Liam's Chowder House <i>and<i> Grill. The document contains two references (&test;) to this entity. A plain text version of this document is available at data-1.txt.
• data-2.xml -- The same document as above, but containing a reference to (&test2;) an entity that is not declared in the DTD. This results in a fatal error to any XML processor. A plain text version of this document is available at data-2.txt.
• data-3.xml -- The document data-1.xml, modified to define two external entities (part and part2). However, only part has actual data at the indicated URL (stuff.xml) -- the URL associated with part2 does not point to anything. This is fine according to the XML specifications, so long as the XML processor is not validating the XML. A plain text version of the document and external entity are available at data-3.txt and stuff.txt.
• data-3.xml -- The document data-1.xml, modified to define two external entities (part and part2). However, only part has actual data at the indicated URL -- the URL associated with part2 does not point to anything. This is fine according to the XML specifications, so long as the XML processor is not validating the XML. A plain text version of this document is available at data-3.txt.
• data-4.xml -- The document data-1.xml, modified so that the DOCTYPE declaration references an external entity (ents.dtd) containing the entity declarations. A non-validating XML processor can chose (or not) to retrieve and process this resource. A plain text version of this document and the DTD file are available at data-4.txt and ents.txt