紫微
Zi Wei Dou Shu describes a person through a chart of twelve palaces, with fourteen major stars and a large supporting cast of auxiliary and malefic stars. It takes the same birth moment as BaZi but builds the chart from the lunar calendar rather than the stem-and-branch calendar.
The core surviving text is the Zi Wei Dou Shu Quan Shu, attributed to Chen Tuan and compiled by Pan Xiyin in the Ming. The differences between the modern schools can mostly be traced back to which passages of that book each of them chose to follow.
How to read this branch
Get the star-placement rules working before reading the material on what the stars mean. The Four Transformations are what set this system apart from the others and deserve separate attention.