XML in a Nutshell, 3rd Edition

RDDL Syntax

A RDDL document is an XHTML Basic document, plus one new element: rddl:resource . XHTML Basic is a subset of XHTML that includes the Structure, Text, Hypertext, List, Basic Forms, Basic Tables, Image, Object, Metainformation, Link, and Base modules. There are no frames or deprecated presentational elements like font and bold. However, this is enough to write pretty much anything you’d reasonably want to write about an XML application.

In addition, a RDDL document contains one new element, resource, which is placed in the http://www.rddl.org/ namespace. This URL is normally mapped to the rddl prefix. The prefix can change as long as the URL remains the same. However, the RDDL DTD declares the resource element with the name rddl:resource, so a RDDL document will be valid only if it uses the prefix rddl.

A rddl:resource element is a simple XLink whose xlink:href attribute points to the related resource and whose xlink:role and xlink:arcrole attributes identify the nature and purpose of that related resource. The rddl:resource element can appear anywhere a p element can appear and contain anything a div element can contain. Web browsers generally ignore the rddl:resource start- and end-tags, but will display their content. Automated software searching for related resources only pays attention to the rddl:resource elements and their attributes, while ignoring all the XHTML.

Recall the person vocabulary used several times in this book. When last seen in Chapter 8, it looked ...