A more thorough explanation:

Semestria is a term used in Roman law. It refers to the decisions made by Roman emperors every six months. These decisions were collected and recorded for future reference.

• Emperor Augustus issued semestria to regulate the Roman army every six months.
• The semestria of Emperor Trajan dealt with the administration of justice in the Roman Empire.

These examples show how semestria were used to regulate different aspects of the Roman Empire. They were important in ensuring that the empire was governed effectively and efficiently.