RDoc, the native documentation tool of RubyLanguage (''though it can also be used for CeeLanguage'') uses a simple wiki-like TextFilter/MarkupLanguage to produce pretty text.  A subset of RDoc's format is or can be used in most Ruby-driven WikiImplementations and web tools.

http://www.thekode.net/ruby/rdocsite/RDocSiteMarkup.html
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CategoryTextFilter