Predicates are filters that restrict the nodes selected by an XPath expression. Predicates appear inside [square brackets].

Courses

1. /courses/course[@acad_year = 2009][@offered = 'Y']
2. /courses/course[@acad_year = 2009 and @offered = 'Y']

Congress

1. /congress/person[role/@type = 'sen']
2. /congress/person[role/@state = 'CA']

RSS

1. /rss/channel/item[position() = 1]
2. /rss/channel/item[position() = last()]
3. /rss/channel/item[position() mod 2 = 0]
4. /rss/channel/item[position() mod 2 = 0]/title
5. /rss/channel/item[1]/title

XHTML

1. /html/head/title
2. /html/body//a[@href]

What is the difference between the following?

• /html/body//a[@href]
• /html/body//a/@href

Copyright © 2002-2009 David P. Heitmeyer