A more thorough explanation:

Jus tripertitum is a Latin term that means "law in three parts" in Roman law. It refers to the law of wills during the time of Justinian, which was derived from three sources: the praetorian edicts, the civil law, and the imperial constitutions.

Testamentum tripertitum is a type of will that was valid in Justinian's law. It was called "tripartite" because the authority for various parts of it derived from three sources:

• The civil law, which required that the will be made at one and the same time before witnesses
• The praetor's edict, which required that there be seven witnesses and that they must seal it
• Imperial constitutions, which required that the testator must sign at the end

This type of will was made without interruption, with seven witnesses to seal it, and signed by the testator.

In Roman law, there were other types of wills, such as:

• Testamentum calatis comitiis: a will made before the comitia curiata, having an effect comparable to adrogation
• Testamentum holografum: a will entirely written, dated, and signed by the testator
• Testamentum in procinctu: a will made by a soldier before a fellow soldiers while preparing for battle
• Testamentum militum: a will made by a soldier during military service

These types of wills illustrate the different circumstances under which a person could make a will in Roman law.