Could be worth a closer look.
The AS/400 hobbyist community has little in the way of software from
that era (5.25/8-inch suggests AS/400s CISC machine, the later RISC
based machines mostly used CDs as a distribution media, cartridge tape
was used too).
If you are visiting RE-PC could you copy down some of the diskette
labels please, we can get an idea of what it might be.