docs:
http://svnbook.red-bean.com/en/1.6/svn.branchmerge.using.html

creating a test repository:

 @svnrepo:
     mksvnrepo -p testbranching -g lihas
 
 @workstation:
     REPO=https://svn.example.com/svn/testbranching
     mkdir testbranching
     mksvnproject -p testbranching
     cd testbranching
     date >  testfile
     svn add testfile ; svn -m "" commit
     date >> testfile ; svn -m "" commit
     date >> testfile ; svn -m "" commit
     date >> testfile ; svn -m "" commit
     date >> testfile ; svn -m "" commit

This test repository is not very suitable for branching, so 
it has to be converted first:

<code>

    mkdir trunk
    svn add trunk    ; svn -m "+trunk" commit
    mkdir branches
    svn add branches ; svn -m "+branches" commit

    svn mv "$REPO/testfile" $REPO/trunk -m "mv to trunk"
    ->
        Committed revision 6.

    <test>
    svn update
    ->
        D    testfile
        A    trunk/testfile
    => OK
    </test>

    rm -rf .svn trunk branches
    svn checkout $REPO/trunk .

    # jetzt ist der branch "trunk" in dem verzeichnis ausgecheckt.

    svn cp $REPO/trunk $REPO/branches/v4 -m "cp branches/v4"
    ->
        Committed revision 8
    => OK

    svn checkout $REPO/branches/v4 ../testbranching-v4

    cd ..

    echo "minor change" >> testbranching/testfile
    echo "major change" >> testbranching-v4/testfile

    svn commit -m "minor change" testbranching/testfile
    svn commit -m "major change" testbranching-v4/testfile

</code>