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reefraff:Duetches Institut fur Normung (D.I.N.) is a non-governmental German agency not unlike the American Society for Testing and Materials (A.S.T.M.) or the American National Standards Institute (A.N.S.I.) here in the states. They set standards for a wide range of things, including the threading used in what we refer to as DIN valves. The standard is complex: beyond thread count, there are rigid specs for the depth of the threads, the width of the valleys and threads, the angle of the threads, etc. To get the whole picture, you're supposed to purchase the standard, just like you would buy a standard from ASTM or ANSI.
Google DIN and you'll get a lot of hits from places that would love to sell you whatever you need or you can go directly to the source.
All of which is a long way of saying that I don't know exactly what the standard is, of course.