CMX file format documentation

[Alex]

Is there some kind of SDK or documentation on CMX file format?

[squonk]

The CMX browser and .PDF documentation that came with X3 date back to 1998.
The CMX format placed in the clipboard by Copy is in some aspects different from the format used when saving in a file; e.g. the CMX browser does not read it quite well (File - Open From Clipboard).
The question is still the same: is there an up-to-date documentation on CMX format?