DOCBOOK-APPS: Newbie Question about Bibliomixed Entry

[Elliott Branch <ebranch at amciweb dot com>]

Title: Newbie Question about Bibliomixed Entry

I work for a small company that does training and consulting on management issues for the Federal government. We are experimenting with DocBook as a way of reusing training content.

I am trying build a bibliography for some training material that I working on so I went to DocBook: The Definitive Guide for some help. Unfortunately, I'm too newbie-dense to understand the following example (page 51, printed edition):

<bibliomixed>
  <bibliomset relation=article>
    <surname>Walsh</surname>, <firstname>Norman</firstname>.
    <title role=article>Introduction to Cascading Style Sheets</title>.
  </bibliomset>
  <bibliomset relation=journal>
    <title>The World Wide Web Journal</title>
    <volumenum>2</volumenum><issuenum>1</issuenum>.
    <publishername>O'Reilly & Associates, Inc.</publishername> and
    <corpname>The World Wide Web Consortium</corpname>.
    <pubdate>Winter, 1996</pubdate></bibliomset>.
</bibliomixed>

I'm okay with the structure and the elements; it's the attributes that are giving me trouble. What is the purpose of   relation and role, respectively in this example? How would use them with respect to the rest of the document structure?

Thanks,

Elliott Branch