I want to know the answer to the following question:
When was the title of cardinal reserved for the cardinals of Rome by Pius V?
All the background I'm provided with is that "The earliest example of this occurs in a letter sent by Pope Zacharias in 747 to Pippin III (the Short), ruler of the Franks, in which Zacharias applied the title to the priests of Paris to distinguish them from country clergy.". Is that enough to answer the question?
Answer: no