This documentation was written to describe Subversion 1.0. If you are running a newer version of Subversion, we strongly suggest that you visit http://www.svnbook.com/ and consult the version of this book appropriate for your version of Subversion.
Unlike CVS, a Subversion working copy is aware that it has checked out a module. That means that if somebody changes the definition of a module (e.g. adds or removes components), then a call to svn update will update the working copy appropriately, adding and removing components.
Subversion defines modules as a list of directories within a directory property: see the section called “Externals Definitions”.