Task: Question Generation
Input (English): In cities other than Rome, the name cardinal began to be applied to certain church men as a mark of honour. 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. This meaning of the word spread rapidly, and from the 9th century various episcopal cities had a special class among the clergy known as cardinals. The use of the title was reserved for the cardinals of Rome in 1567 by Pius V.
Output (English): In regards to the word "cardinal" being used in cities other than Rome, who sent a letter to Pippin III?