Final answer:
Diocletian subdivided the Roman Empire's provinces into smaller units called dioceses, overseen by vicars. This structure influenced the administrative organization of the Catholic Church, which still uses this system today.
Step-by-step explanation:
As Diocletian made more administrative reforms, he further subdivided the provinces into smaller, more governable units called dioceses. The significance of this lies in the influence it had on future administrative structures, notably the Catholic Church. When Christianity became the official religion of the Empire, the Church adopted the concept of dioceses and vicars for its ecclesiastical management, a system which continues to this day.
The administration of the Roman Empire underwent significant changes with Emperor Diocletian's reforms. He divided the empire into smaller provinces, which were grouped into larger units called dioceses, each overseen by an official known as a vicar. This administrative structure outlived the empire itself, as later institutions like the Catholic Church would adopt and maintain it throughout history, illustrating Diocletian's lasting impact on organizational governance.