Why is Song Ti not called Song Shu?

Song Dynasty is not called Song Shu because Song Shu is a biographical history book that records the history of Liu and Song Dynasties in the Southern Dynasties, so it cannot be called Song Shu. In fact, Song Style is not a font in Song Dynasty, but a special term in typology, which refers to a font formed in the middle of Ming Dynasty by imitating Zhejiang seal cutting in Song Dynasty.