InterWikiLink is a way to link to other Wikis. On this Wiki, the syntax is simply:

[name of the wiki:page on that wiki]

So, for example, if you want to link to the original Wiki on Portland Pattern Repository, just say: WikiWikiWeb:WelcomeVisitors, or to TWiki, say TWiki:Main.

A list of available InterWiki links can also be seen on the SystemInfo page.

To get the below list use:
[{$interwikilinks}]
Available InterWiki links
TWiki --> http://twiki.org/cgi-bin/view/TWiki/%s, WikiWikiWeb --> http://c2.com/cgi/wiki?%s, Reader --> Wiki.jsp?page=%s&skin=reader, Wikipedia --> http://www.wikipedia.com/wiki/%s, Raw --> Wiki.jsp?page=%s&skin=raw, Doc --> http://jspwiki-wiki.apache.org/Wiki.jsp?page=%s, Google --> http://www.google.com/search?q=%s, JIRA --> https://issues.apache.org/jira/browse/JSPWIKI-%s, RSS --> rss.jsp?page=%s&mode=wiki, Group --> Group.jsp?group=%s, Edit --> Edit.jsp?page=%s, Location --> https://maps.google.com/maps?q=%s, MeatballWiki --> http://usemod.com/cgi-bin/mb.pl?%s, JSPWiki --> https://jspwiki-wiki.apache.org/%s

To add a new InterWiki link, add to your jspwiki.properties configuration file the following syntax
jspwiki.interWikiRef.WIKINAME = WIKIURL?page=%s
For example:
#  Wikipedia, a Wiki encyclopedia!
jspwiki.interWikiRef.Wikipedia = http://www.wikipedia.com/wiki/%s

#  Google, the ubiquitous search engine.
jspwiki.interWikiRef.Google = http://www.google.com/search?q=%s

# JIRA Issue Tracker
jspwiki.interWikiRef.JIRA = https://issues.apache.org/jira/browse/JSPWIKI-%s

You can also see some useful InterWikiLinkTips.