I don't see a problem with that, but I wonder if - functionally speaking - B and C have to be common tolerance zones. While B as a CZ could make some sense, I doubt that the C planes really require to make common contact.
ISO 2769:1973 is something completely different ("Modular units for machine tool construction").
What you mean is the German standard DIN 2769:2023-04 (that is the most recent). It is meant to be an addition to ISO 22081 and provide tolerance examples, but it is not yet adapted internationally.
No, and it shouldn't even be an issue anymore, since ISO 2768-2 has been withdrawn, and ISO 2768-1 might follow in the future.
New projects should use ISO 22081, which supplies only the rules for a more unambiguous use of general tolerances but no values. It is now up the designer to define...
The way a datum system is made in ASME vs. ISO is extremely similar.
One difference is in fact how a plane is used. The latest ASME standard will use a so-called L1 algorithm as a default, which is basically a filtered Gaussian plane extended to one or more highest points. The older ASME...
