A hybrid approach might also fulfill requirements of a preservation standard.
For example, information required to identify and decode the rest of the stored data might be placed on these Pancake disks in both digital and analog formats.
But what about this UPF? What does the thing look like?
I will give a simplified overview of the important characteristics: the Wrapper, the Rosetta Stone, and Unique Identifiers, and a Media Compiler.
The wrapper -- or container -- is a file format for storing both the media content or "essence" along with the information that describes it. Think of it as kind of a digital fahita or burrito with the basic ingredients as the "essence" and the optional hot sauce as its metadata.
The wrapper is both a file format and a framework.