Azo refers to azo porosity, (1 150- 1230), a representative figure of annotation law school.

Western academic circles generally believe that although the historical origin of modern western jurisprudence is Roman jurisprudence, its direct origin is the Annotation School of Law led by Inarius, a teacher of Bologna University in medieval Italy. Thanks to the efforts of Annotation Law School, a bridge has been built between Roman law and modern law.

The annotator school was born at the end of 1 1. Its founder is ignatius (about 1055- 130), a teacher at the University of Bologna. The representative figures are Azo Porous (about 1 150- 1230) and Accursius (about 1 1260).

It was Azo and Acusius who made great contributions to the school of annotation law and finally determined it. Azo was a student of Bassanios (Inarius's great-grandson) and became a professor of civil law at the University of Bologna after graduation. On the one hand, he inherited the mainstream position of teachers, on the other hand, he also paid attention to absorbing the achievements of non-mainstream schools represented by Gao Sai, one of the four doctors. Therefore, the school of annotation law reached the peak of development in his hands. The Annotations and Explanations of Justinian Code and Justinian Jurisprudence Ladder compiled by him have won a wide reputation not only in Italy, but also in Europe as a whole, and become indispensable books for court participants. Therefore, there was a popular saying at that time: "Don't enter the palace (court) without reading the book of Azuo". In fact, in Azuo's time, annotated jurisprudence has developed for more than 100 years, so a large number of works annotated The Complete Book of Roman State Law appeared. Among them, quite a few works have left the annotations of the original Roman law, but only the annotations of their teachers, thus making Roman law more complicated and chaotic. In order to make up for this defect, Azuo decided to make a second annotation on the Complete Collection of National Laws. To this end, he created an annotation integration about the Justinian Code and the Justinian Law Ladder. Although, western scholars have been arguing whether Azo's works copied the works of his teacher Bassanius and others. But it is true that his works were widely welcomed by European countries as soon as they were born. Even in Britain on the other side of the ocean, H.D. bratton (about 12 16- 1268), a famous jurist in the 3rd century, wrote the famous book "On the Laws and Habits of Britain" (Delegibus Etconsuetudobus Anglia libriquinque, 6544).