What does Zhen Xuan mean in calligraphy? What happened to Zhen Xuan?

It is a writing method, that is, when writing with a brush in hand, the hand leaves the paper and hangs to write, just like a needle hanging upside down, hence the name "hanging needle". There is also a vertical stroke in calligraphy, which is called hanging needle vertical. The external image is a needle, which is thick on the top and thin on the bottom, just like hanging needle. The advantage of hanging needles is that it is convenient to write larger words, which is more difficult. First of all, the wrist should be strong and the font structure should be skilled, otherwise it will be difficult to master.