Originally Posted by Ghrumpy

Well, not exactly. Campagnolo's pre-1994 taper is not that close to JIS. It may be close enough to "work" but it's not exactly what I'd consider "interchangeable."

The Campy taper is symmetrical, like JIS, whereas ISO isn't. But really it's somewhere between the ISO and the JIS. It's slightly bigger on the end than ISO but smaller than JIS. But it's a shorter taper than either.

As I've written elsewhere, it's a mistake to think of any pre-standard European taper as adhering to any standard; every company had their own. ISO is a compromise taper designed to work with as many "legacy" European cranksets as possible, from TA to Zeus, but is not exactly the same as any of them. (This is why the ISO has a longer DS taper, to accommodate TA and Stronglight.)
OTOH you can say the JIS taper is exactly the same as the Sugino "Maxy" taper, because it was the de facto Japanese BB taper when the JIS was adopted. (It's pretty much an exact copy of the right side Stronglight taper, FWIW, and nobody would say the Stronglight taper is the same as Campagnolo, would they? I wouldn't.)

Then again, these standards are not compulsory. Even in Japan, Suntour made their "Superbe" taper after JIS was adopted, and Sugino still make non-JIS cranks that fit only their "Mighty" taper BB, which is a very close copy to the Campagnolo. It's not close to JIS.

The unfortunate truth is that if you're trying to use a pre-standard crankset with a post-standard BB (or vice versa) you just have to try them out to make sure they will fit. You can't always depend on what a particular web site says. Older cranksets might have been overtightened and the taper hole expanded, so what might work on paper may not work in real life.