So from today's research it seems if you are designing for a fuse-supplied system you would be looking only at Tables B3 (industrial, Ryefield boards, etc) or B4 (domestic) in the OSG as "current" new products.
Though they still have the older tables for rewirable in B1 (which I would hope not to have to deal with!) and the older standards for fuses in tables B2 (industrial, I guess?) and B5 (domestic).
I also guess this explains the difference between the industrial sized fuses that are usually the same size for a big range of currents, and the domestic that often are different body sizes per rating to reduce the chance of incorrect replacements being used.