Existing .DSF files are compatible with 4.5 I assume?
It seems like the full DSON format is a superset of what we have in current .DSF files, from what I’ve seen in there.
Yes, DSF files produced by the current production release of DAZ Studio 126.96.36.199 (which implements the unpublished 0.5.0.0 DSON spec) are compatible with the DAZ Studio 4.5.x Release Candidate. They do not conform entirely to the 0.6.0.0 spec, but we have done a bit of work to keep backward compatibility.
Yes, DSON describes the entire format and the various file types (*.duf, *.dsf) implement the applicable portions of that format.