A more thorough explanation:

Magistratus minores were officials in ancient Rome who had limited powers. They were not as important as the magistratus maiores, who had more authority. The magistratus minores had specific jobs and could only do certain things. For example, some were in charge of public buildings, while others were responsible for making sure people followed the rules about weights and measures. Serving as a magistratus minor was a way for people to start their careers in government and work their way up to more important positions.