The original meaning is "your collar". It first refers to a woman's nickname for her sweetheart, and later refers to intellectuals and scholars. This is a representative poem in The Book of Songs, which was quoted by Cao Cao. These four words are the names of poetry columns, which have the most romantic atmosphere on campus. Their names are poems at a glance, and their meanings are campus at a glance. There are puns, and they are never vulgar.