I hope magnetoman doesn't read this thread............
have never seen the logic to look up files about bolt threads to know the type of hexagon and spanner. In metric world nobody cares about threads, you get your vernier onto the hexagon and see in same second what size of spanner you take
Logic? You own a British bike and you expect logic?
OK, you obviously approach working on your bikes differently than I do. You carefully measure the size of the metric hexagon with calipers then select the size of the spanner that fits. I can understand why you do that, since it ensures you never make a mistake. In contrast, with my British spanners I haphazardly select the spanner than looks like it will fit, and if I discover I made a mistake and it does not fit, I select the next size larger or smaller, as appropriate.
The difference is, with your technique you never make a mistake when selecting a spanner from the tool box, but mine leaves me wide open for making mistakes. Clearly, your technique is much better so, in light of your post, I will make an improvement to my technique. From now on I'll use digital calipers to measure the hexagon of the British fastener, look up the corresponding BS or BSW size (some of my spanners are stamped with both, but others are stamped either just BS or BSW, so two sets of tables are needed), and from now on unfailingly select the proper spanner from the toolbox. No more mistakes for me!
Addendum: In light of your post I should be ashamed to admit the following, but I'm shameless. For twenty years I've kept a BSA in Ireland to use in the annual Irish Rally. Over the years the bike has acquired a mix of fasteners, but I put together the following set of ¼"-drive sockets for the toolkit that I carry on the bike, that fits all the BA, BS, BSW, CEI, and A/F fasteners across the relevant size range within acceptable, but definitely non-Germanic, tolerances:
5/16", 11/32", 12 mm, ½", 14 mm