Finally UDDF 3.0 was released on March 14th, you can find the Spec here:
http://www.streit.cc/extern/uddf_v300/en/index.html
I provided an schema file (xsd) to the project, that can be used for validation and bean generation.
I also use this schema to create a converter for my AquaDiveLog Files (AquaPalm-DiveDB.pdb, AquaPalm-TableDB.pdb) to UDDF 3.0,
but this is work in progress....