When you use the project archiver (the first option for "used" material) all subclips become real clips--actual disk files.
Applicability: general, but particularly if some or all the source(s) of a project were non-digital and hence one very large "clip".
*Suggested use No. 1: on a nearly completed project that has subclips galore and you are confident you will not need the original pieces again or stretch any of the subclips, "archive" it and then use the archived version to complete the project.
*Suggested use No. 2: From a non digital original source that covers more than one major topic, bring the huge original (typically through a Pyro from a VHS tape) into PRel. Make two (or more subclips by drag to monitor, set in/out points and back to media bin. IF you did it right you will now have giles something like xxxsubclip001 and 002 OR even better what you named them when making the subclip. PUT ALL THE SUBCLIPS on the timeline!!!! Archive it. You will now have two or more clips and can (cautiously) get rid of the original, then you can start work on the two or more unrelated projects that were on the original source.