A local repository of external project files. Generally contains only compiled (binary) files like Jars, but may include other artifacts like DTDs and XSD files. See the entry on the <library-repository> task for more details about setting this up.

There can be as many repositories as needed. They process the library entries (looking for their filesystem counterparts) in the order they appear in the Ant build file.

This element can also be a reference to any other repository type, by using the "refid" attribute.

A special kind of repository that allows for a remote repository with a local cache. See the entry on the <urlrepository> task for more details about setting this up.

A special kind of repository that emulates the Maven repository usage, allowing for a remote repository with a local cache. See the entry on the <mavenrepository> task for more details about setting this up.

For completeness, you can add a <repositoryset> entry, although its usefulness is more for outside the libraryDef than inside it. It can also be used for logically containing different repository groups, if needed.