Typically, a release's lineup of applications is defined when the release is created. Applications associated with the release are automatically available to any deployment using the release. Applications and applications suites can be promoted to released versions. Typically, a released version represents an application (or suite) that has been successfully deployed and can reliably be reused.
Additionally, you can add applications to a release after deployments have been scheduled for it. New applications become part of any upcoming or in-progress deployment.