Zhang Xu befriended Li Bai and He Hao, and Du Fu listed him as the "Eight Immortals of Drinking". Zhang Xu is a master of cursive script with great personality. Because he is often drunk, clamoring for madness, then writing books, and even writing with his hair dipped in ink, he has the nickname "Zhang Dian". After Huai Su inherited and developed his brushwork, he was named after cursive script, and called it "Dianzhangzuisu" (or "Dianzhangkuangsu").
Zhang refers to Zhang Xu, a calligrapher of the Tang Dynasty, who is always called Huai Su, a calligrapher of the Tang Dynasty.
The nib refers to the characteristics of Zhang Xu's calligraphy: passion erupts, even to the extent of madness.
Drunk refers to the characteristics of Huai Su's calligraphy: round and flying, ethereal and transparent charm
This idiom means that a person's character is outstanding, and it is also used to praise cursive calligraphy works with the charm of Zhang Xu and Huai Su.