Unified coding. Personal identification code (19 digits) is a unified code for basic information of education system personnel, which consists of type code (1 digit) and citizen identification number (18 digits) or personal identity self-coding (18 digits) According to these rules, the Ministry of Education gives the educatee an educational identity number, and the personal identity self-coding (18 bits) is a characteristic combination code, which consists of a 17-bit digital ontology code and a check code.