I managed to check out my question regarding landing at a lower altitude than T/O point (HOME POINT) and then pressing RTH to get back (to your original point of departure). Many of you probably are fully aware of this but as being new to this kind of flying I wanted to check it out, here was the result. I took off and made a short flight around my immediate area pressed RTH and as expected the P4 obeyed, it flew to the pre-set RTH altitude above take off and setup its landing and landed (where it departed from), perfect! I then took off again from the same (original) point, I flew the P4 around a bit (during this flight I also had chance to test the object avoidance system, I flew it at a truck trailer of mine, it worked fine). I then proceeded to land the P4 where we were some 20 or so feet lower than the original T/O point. I landed (being sure to keep the props going, so I did not need to arm the motors again for T/O). I pressed RTH to see if the P4 would take off and fly back to where we came from (the original T/O point). THEN IT ALL BECAME CLEAR . . . The answer to my question. Having landed in this NEW spot (even though the motors were kept running) the software had adopted/registered this lower landing point as the 'HOME POINT'. To get back to where I originally took off I had to take off and fly back to the previous T/O point and land there (where the software again registered this [the original] landing point as the now new 'HOME POINT'. As I've said above, many of you probably knew all of this but for those of us that are comparatively new here it was a good experiment and I learnt from it, I hope some of you will too.