DIN 7643 is compression couplings–Hollow screws for ring-type banjos. The banjo bolt is mate with banjo fittings and washer together, banjo bolt leaking is main reason of installation.
Many banjo supplier and manufacturer often choose DIN 7643 standard for many industries as follows:
Hydraulic banjo fittings
Banjo blot fuel line
Banjo hose tails
How to measure banjo fittings as per this standards?
Here is drawings: