Since last article has introduced this 《玄空秘旨 Xuan Kong Mi Zi》 clasical literature for xuan kong fengshui study reference, I would like to remind here that there are two versions available, one version was recorded in the Ching Dynasty Xuan Kong master Zheng Zhong Shen 章仲山's book《心眼指要 xin yan zhi yao》, commonly used and refer to nowadays. Another version already existed at much earlier time than Zheng's version.
Just from the begining several sentences of both.versions (see below) can.see.the differences already. There are other differences in several writtings.and contents between both,. Nevertheless both drive to the same xuan kong principles.
Zheng's version
不知來路，焉得入路，盤中八卦皆空。
未識內堂，焉識外堂，局中五行盡錯。
乘氣脫氣，轉禍福於指掌之間。
左挨右挨，辯吉凶於毫芒之際。
一天星斗，運用隻在中央。
千瓣蓮花，根蒂生於點滴。
Older version
不知變易，但知不易，九星八卦皆空﹔
不識三般，那識兩片，凡屬五行盡錯﹔
顛之倒之，轉禍福於指掌之間﹔
左挨右挨，辯吉凶於毫芒之際﹔
一天星斗，運用隻在中央﹔
九曜干支，旋轉由乎北極。
My original article written in chinese can be found at:
http://tiensum.blogspot.sg/2014/07/blog-post_9655.html?m=1