9th Parts (Novenaria)

1
I am rather familiar at this point with the Navamsa and how it is used but I am curious if anyone has done any digging and experimenting with the 9th parts described in various medieval texts (Bonatti, Abu Mashar, etc). It is interesting to me that the Persian/Arabic astrologers emphasized the planet ruling a specific 9th part whereas in India they get a whole new chart from the 9 fold division and interpret it as its own chart while relating it back to the natal. I have been using the 12th parts in the manner outlined by Firmicus with great results and it appears he does make some mention of the division of each decanate by 3 as a refinement technique, but the question is how was this technique used. Has anyone gotten any results with it?

3
Thanks, that is all very useful information. From what I have been able to gather the 12th parts were used by certain astrologers as secondary zodiacal positions relative to the radix. These 12th parts do indeed give a lot of very pertinent information not otherwise found in the chart (again this is through my own experience). So it's almost as if the 12th parts are showing us a more refined version of the natal chart, so to speak. I have been, however, unable to find any medieval sources that explain how the use of the 9th parts may differ from that of the 12th parts and why the 9th parts focus on the planets rather than the signs. In Jyotish (perhaps this is a more modern aspect of the technique) it seems that the Navamsa is said to be the fruit, or the quantity/quality of the results, of what is shown in the radix. It is given almost as much importance as the radix and also seems to be very important for predicting marriage. Basically, for the purposes of my own practice, I am probing for clues about how I could employ both 12th parts and 9th parts so that they do not get in each others way. Perhaps the 9th parts refer more to the fruit, as people seem to say, whereas 12th parts show us contraindications for zodiacal positions. Therefore 12th parts would indicate other areas of life the planets operate and by their zodiacal position if they are in fact better or worse than they appear at first glance, while the 9th parts, if used zodiacally like a navamsa, might instead show a more temporal development of what is indicated by the chart. The distinction is subtle but it may be very real. However these are just theories and so I seek to know if anyone has experimented with these two techniques, side by side, within the Persian/Arabic methods of astrology.