Hi Louis,
Thanks for your questions on descriptions of the DSSR JSON output. As you noticed, DSSR derives (far) more features than those already documented in the 108-page User Manual. That's on purpose. DSSR contains many unpublished results, as well as a lot of experimental functionalities. On the other hand, some features already documented in the DSSR User Manual may not have been read as I'd expect. Overall, I do want to ensure what have been documented and published to be accurate and reproducible.
For nucleic acid structures, see "Principles of Nucleic Acid Structure" by Wolfram Saenger. For 3DNA/DSSR, read the 2003 NAR paper on 3DNA, and 2015 NAR paper on DSSR and the DSSR User Manual.
Best regards,
Xiang-Jun