Container-less Content? Not in This Digital Age.
Frames span digital and analogue, piles of loose paper and bound books, CDs and sheet music, postcards and Picassos, MySQL databases and physical storage. Just as publishers choose frames in terms of demy hardbacks, B-format paperbacks, cover art, page design, typesetting, and typography they might also chose frames in terms of iOS or Android builds, interface design, and rendering quality. Frames allow us to view digital and analogue media on a spectrum rather than unbridgeable islands, to see how not only do highly divergent forms of published material all require delivery systems but how those systems present works in differing ways.
Frames have a presentational or performative aspect to them; they don't just deliver a work but deliver it in a certain way. The OED, finely bound, proudly embossed with the great golden crest of OUP, sporting huge page cuts, makes a statement about what the OED is and does. This presentational quality is part of why we can talk of frames as object nonspecific, essentially a presentational mode as well as a medium.
Frames as distribution systems -- like books or MP3 files and players -- gesture toward the ways in which frames and content are mutually involved yet also distinct. Frames condition content and vice versa. Novels and books have typically been a prescribed length because it was convenient for the codex, amenable to realistic print runs and hence economical, all of which is to say, the set of possible frames dictates what is possible for content. Equally, content looks for new frames. Content creators don't passively wait for frames to evolve -- they make it happen.