[sltkr]

So basically just IFF/RIFF with fields exchanged?

See:

  http://en.wikipedia.org/wiki/Interchange_File_Format

  http://en.wikipedia.org/wiki/Resource_Interchange_File_Format

[daeken]

The big difference between the QT Atom structure and RIFF is that RIFF is a series of independent chunks (IIRC), whereas Atoms are a big tree. Structurally nearly identical, though.

[vidarh]

Don't know about RIFF, but IFF files are/can be a big tree - the outer chunk must be one of FORM, LIST or CAT, and many chunk types contain additional chunks, so depending on the file you might get structures of arbitrary depth.