How can I cause subversion to check out projects from other repositories?

I recently was working with a subversion project that checked out code not only from the repository I was working with, but also from a separate repository on a different server.

How can I configure my repository to do this?

I'm using the subversion client version 1.3.2 on Linux, and I also have access to TortoiseSVN version 1.4.8 (built on svn version 1.4.6) in Windows.

See svn:externals:

Sometimes it is useful to construct a working copy that is made out of a number of different checkouts. For example, you may want different subdirectories to come from different locations in a repository, or perhaps from different repositories altogether. You could certainly setup such a scenario by hand—using svn checkout to create the sort of nested working copy structure you are trying to achieve. But if this layout is important for everyone who uses your repository, every other user will need to perform the same checkout operations that you did.

Fortunately, Subversion provides support for externals definitions. An externals definition is a mapping of a local directory to the URL—and possibly a particular revision—of a versioned resource. In Subversion, you declare externals definitions in groups using the svn:externals property. You can create or modify this property using svn propset or svn propedit (see the section called “Why Properties?”). It can be set on any versioned directory, and its value is a multi-line table of subdirectories (relative to the versioned directory on which the property is set) and fully qualified, absolute Subversion repository URLs...