Created a branch in my main repository yesterday after running trials on a sample repository. Things snapped into focus after reading Key Concepts Behind Branches from the SVN book, which reinforces the point that Subversion is a versioned file system, and a branch conceptually is merely a copy.

svn copy http://localhost/svn/ll/trunk http://localhost/svn/ll/branches/gui
cd wkgDirectory
svn switch http://localhost/svn/ll/branches/gui

Everything worked as advertised and the copy added only 5% to the repository size, since files aren’t duplicated until a modification is committed. The documentation says that individual directories and even files can be switched. Directories worked but individual files turned into working directories?