Where did the 156 mil / 3.96 mm pin spacing standard come from?

Question

Along with countless sensible pin pitches like 100 mil or 2 mm or 200 mil, on certain things like card edge connectors and terminal blocks, a pitch of 156 mil is common. But where did the number 156 come from? You would think they'd go for 150 mil, or 4 mm (157.5 mil), but no, it's very specifically 156 mil or 3.96 mm, and in fact, 150 mil spacing is (going by the number of results on digikey) much less common than 156 mil.

Where did the 156 mil standard originate?

Answer 1

I believe it comes from \$\frac{5}{32}\$ of an inch or 156.25 mil/thou.or 3.96875 mm. And, it was probably changed by a committee of senior managers to 156 mil/thou.