Apart from the imperial gold plate, what did the Southern Song Dynasty do to ensure the smooth flow of important official documents?

In addition to the imperial gold plate, the Southern Song Dynasty also made some other plates, and it was stipulated that no one was allowed to deliver them in a hurry without a plate to ensure the smooth flow of important official documents. In the third year of Xiaozong Road (1 167), black paint and white powder cards were made and distributed to the state military departments for use, which was specially used to report the emergency military situation to the court. Five years later, they made an orpiment version for the court to use when sending urgent official documents to various places. In the fourth year of Guangxu (1 193), a black painted scarlet letter card was issued, engraved with "Privy Council Sketch Card" instead of a badly worn black painted white card. This system of "delivering with the card" distinguishes urgent documents from general documents and ensures the smooth flow of urgent documents, which is a major feature of the military communication system in Song Dynasty. Sadly, this pioneering work in the history of military communication did not help the Song Dynasty achieve military victory, but was linked to an unprecedented tragedy in military history because of the serious mistakes of the supreme ruler. The regret of the gold medal has aroused the infinite lament of future generations!