Markup format used in ZoPe, now available in ZWiki too. Plain text with markup conventions which allow it to be rendered richer formats such as HTML while being still being very easy to read and write in its original form. Similar to WikiWikiWeb's markup format.
Here are the StructuredTextRules, from the source.
Here is the structured text HowTo on zope.org.
Here is a StructuredTextExample.
See also ZWikiWeb:StructuredText