Getting help:

svn help
svn help merge
svn help copy
svn help status

Finding a 'base' revision of a branch ( -v [--verbose] )

svn log -v --stop-on-copy http://www-pcmdi.llnl.gov/svn/repository/cdat/branches/mccoy | more 

Finding the curret revision

svn info | grep Rev

Finding the URL of your repository

svn info |grep URL

Finding the history of a file

svn log -v file

Show status of a file

svn status -u -v tar-1.14.tar.gz

Checking out new working copy

svn checkout http://www-pcmdi.llnl.gov/svn/repository/cdat/trunk cdat_trunk

#from repository (for example trunk) to the local working copy:
svn merge --dry-tun -r fromRevision:toRevison http://from_http to_directory
#from working copy to the repository (for example trunk):
svn merge --dry-tun -r fromRevision:toRevison from_directory http://to_http 

Commit changes with a message in a command line ( -m [--message] arg )

svn commit -m "Merged trunk changes r3434:5730 into branch mccoy"

Createing new branch

svn copy http://www-pcmdi.llnl.gov/svn/repository/cdat/trunk  \ 
         http://www-pcmdi.llnl.gov/svn/repository/cdat/branches/mccoy \ 
         -m "Creating a new private branch of cdat/trunk @ revision 5733"

Deleting old branch

svn delete http://www-pcmdi.llnl.gov/svn/repository/cdat/branches/mccoy \ 
       -m "Removing my old personal branch. The repository is @ Rev 5732."

Resurecting an old file

svn copy --revision 807 \
           http://svn.example.com/repos/calc/trunk/real.c ./real.c

Use also CDAT Trac browser to browse the branches and revisons of CDAT software.

For more on subversion see  Subveresion Complete Reference  in the online book:  Version Control with Subversion