Doing some work that can’t be done in trunk in small increments? Then it time to branch.
Say your working on bug “12345 Wibble”…
Step 1: Create the branch
Create a branch of trunk, making a note in the commit message of the revision of trunk the branch is being created from:
svn copy -r 20000
svn://svn/trunk
svn://svn/branches/trunk_wibble/
-m "Bug 12345 Wibble [...]