The most important option for using variants for software releases is the fall-back path assigned to your variant criteria values. The fall-back path defines how Author substitutes objects if a match for the current filtering is not available. It works for both regular releases and branched releases.
The example on the left shows variant criteria values without a fall-back path; if a variant match is not available then the primary object is used. The example on the right shows a fall-back path for a release cycle. With a fall-back option, if a variant match is not available for the current filtering, Author will look for the next best option, working back through your releases based on the path you define.