Hi Kate,
Early on, when I started SFQ, I had the same question. 'Most' systems and written information available, place it below, as opposed to behind. Perhaps all of them...At the time, I had some correspondence with this daughter of this well known qigong master, and posed this question to her. She was very accomplished herself. She had a very simple response, that made me feel sort of silly. She didn't say this specifically, but , say , you have a right knee, and I do. Wouldn't it be silly for me to ask 'you' where 'my' right knee was? I realize that a dan tien is perhaps not as obvious, but, she was letting me know I should be able to tell where my lower dan tien was. If I couldn't, who could.. ! After all, it is my lower dan tien. After this , I started paying more attention to what I 'felt' , as opposed to intellectually defining the location based on what I was being told. Myself, I found , in feeling, places it where Master Lin locates it, behind my navel. Even my navel seems more sensitive an area, and I have always thought, for instance, about the emblical chord one comes in with, if it is relative to this (or not),... but for me, this placement works. The final answer she gave me, was, place it behind the navel for SFQ, and if you do another system that places it below, place it below. Although that makes sense, I myself can't exercise that, and ultimately made a choice. Now my choice is accompanied by feeling that seems to support it.
I have run into this with other things. Let me mention another example , that might reinforce what I said above. All the first nation tribes use the four directions. Althought there is great similarity, different colors and attributes to the directions vary from tribe to tribe. I was with a Lakota friend once, who was talking about his tradition, given the four directions. They were different then how I was taught. He simply said, "This is how they were 'given'(connected) to you. or how your relationship was made with them by 'your' teacher. (Hence) This is how they are for you." So, it connects to how you were given the information, and whether or not you choose to align with that connection, or honor it..
How about, what shape is it? Or does it have physical form? How I 'see' it, internally, is not always the same. Usually it seems like an orb or ball of energy, but I have also seen it as , an expansive sea or sea of chi, or, a palace belonging to one of the three pure ones...depending on one's inner vision and preference in that inner vision. It is a fact that, that physical area of the body can swell, as one accumulates qi.
love,
gallen
