Is there a standard similar to DIN 603 / ISO 8678 (metric mushroom head square neck bolts) for sizes smaller than M4. DIN 603 only goes down to M5 (please correct me if I'm wrong).
I did see similar mushroom head bolts used in piano actions (which is what I want them for as well) but I can't find any more info than that.
Basically what I'm trying to find is something like M4 screw/bolt with a smooth mushroom cap and without any driving features (no slot). Like a DIN 660 rivet but with threads. Or a small DIN 603 bolt.