Historically there are three categories of approach for cultivating the elixir: the heavenly approach (i.e. the golden elixir), the earthly approach (no information, probably lost), and the human approach (i.e. the inner elixir). All Chinese alchemy schools known to us today belong to the inner elixir approach.   

     And there are basically two lineages: the Wenshi School  and the Shaoyang School . Wenshi School is considered highest but there are only very few practitioners of this lineage. Most of the Taoist schools we know today are derived from the Shaoyang School.

     According to the famous 11th century immortal Zhang Sanfeng , the lineage of the Wenshi School have been passed on from Lao-tzu Guan Yinzi  Li Huo, the sack-clothed   Chen Xiyi  Fire Dragon, the man of reality  Zhang Sanfeng, who is also famous as the founder of the inner school of Chinese martial arts and Tai Chi Chuan.   Zhang Sanfeng had also learned the Shaoyang School approach, so later on Wenshi School became mixed with the Shaoyang School. To my opinion, the original Wenshi School approach should be that of the golden elixir.