This is all fairly academic, but to extend the 8.3 filename system I see only three basic places to keep the extra information: a) in an auxiliary file b) in directory entries and c) in the file itself.
The 4dos description system is an example of a), and many others can be found. c) is inherently not compatible. b) using previously illegal entries is MsDos's way, and a previous example can be found in the change from CP/M 2.2 to CP/M 3.0 (or to my DOSPLUS 2.5) somewhere around 1983 to 1987. In fact the addition of CP/M user numbers is an even earlier example, and came somewhere around 1978.
The above may or may not be examples of prior art and invalidate any MS patents. Since IANAL and especially I am not a patent court, that judgement must be left to others. My personal opinion is that it does invalidate, inasmuch as I cannot conceive that using a previously known technique for a more restricted purpose is patentable. The restricted purpose itself is antedated by at least the 4dos description system. That leaves the usual Microsoft "innovations" area as its usual nullity.