After wandering down to Magick Happens yesterday I dropped in to the Aquarius Rising bookshop for a general browse. While I was there I spotted a book on ritual postures and trance. It got me thinking.
After coming away I have done a bit of web searching and I believe the book I came across was: Ecstatic Trance by Prof. Felicitas D. Goodman, Ph.D, and Nana Nauwald. Two related sites are The Cuyamungue Institute and The Bard of Avalon.
It has prompted me to revist my previous comments on meditation postures. Nothing conclusive yet.