maybe the chainrings-cogs-chains are on another standard for Campagnolo. For the rest usually it's OD is 7.77mm - that is standard, the chainrings and cogs engage on the roller, if it was not standard then the chainrings would have slight differences. The internal diameter and pins is not standard as I stated before.
These knowledge does not come from wikipedia or the web, it's found in books, in ISO standards (and other standard, by no mistake ISO, ANSI, GOST, DIN and JIS standards for chains are exactly the same. They are made so to fit chains/bolts/nuts and other small assembly components cross-standards, some of the standards were majority in some days and that hold till present an other standards align to this common standard, some difference still exists in other domains)