can anyone help to illuminate the differences between the g˘maza and kichij˘za postures in zazen. Physically I understand it is it is just the matter of which foot (or hand) is upper when sitting in half or full lotus but are there any more references on the different postures?

I found one reference from Antaiji website http://antaiji.dogen-zen.de/eng/200807.shtml which is useful in discussing about energy flows yin and yang.

Many thanks,