Tang Dynasty official: What does it mean to give purple and gold fish bags to the upper states?

In the Tang dynasty, it was an honor to be a state official. Many generals with outstanding military achievements were appointed as followers, but their actual positions were often below the third and fourth grades. In the Tang Dynasty, the official system was purple robes with three or more products, wearing goldfish bags; More than five robes, wearing a whitebait bag; Green robe under six grades, no fish bag. Officials with high positions and low ranks still wear the original products. For some lower-ranking officials, the emperor can give them purple robes and goldfish bags, which are called "purple-gold fish bags"