How to describe the center with a pen in one sentence?

Let the pen tip travel in the middle of the stroke. Center-stroke writing is a writing method that uses a back-stroke when entering the pen, a hesitant movement in the middle, and a back-stroke when closing the stroke at the end. When writing, it is light and agile, as if the pen tip is walking in the middle of the stroke. The tradition of Chinese calligraphy emphasizing the use of the center pen originated from seal script.