While chatting about data recovery, an obscure filesystem came up. It apparently claimed the MBR partition ID 0x20 and was named "Willowsoft Overture File System (OFS1)". In the modern world, it seems to only be seen when a partition table is corrupted.
Digging back a bit, it's possible to find references to it going back to 2000: https://web.archive.org/web/20000903024208/https://www.win.tue.nl/~aeb/partitions/partition_types-1.html
Rumoured to be used by Willowsoft Overture File System (OFS1), if there is such a thing.
With a possible relation to a "Willowtech Photon coS":
Used for Willowtech Photon coS (completely optimized system) by email@example.com. See dejanews.
A bit more digging and the earliest reference I can find is from 1997: https://groups.google.com/forum/#!search/willowsoft$20overture|sort:relevance/de.comp.standards/upmxnfn2DAs/yXlOFDvXD84J
Unfortunately, this is where the trail gets cold. dezine.net appears to have been a web hosting company. Dejanews was apparently acquired by Google, and not much more is available on Google Groups.
I would like to know where this filesystem was used - was it on an IBM PC-compatible, as the use of MBR suggests? Was it older, or contemporary with PC-DOS/MS-DOS? Did it even exist?