svn? is the commandline client for SubVersioN. It's almost a drop-in replacement for the CVS CommandLine client, but with some necessary differences. The command
svn help
gets you a list of commands and
svn help checkout
gets you help of the checkout command. CVS users will know and understand this style of help. Unfortunately there is no man(1) page to speak of, but there's a very good SubVersion book at 
http://svnbook.red-bean.com/
No other page links to svn yet.
