The so-called "wave potential" and "picking method" refer to the long horizontal direction, which first protrudes slightly to the left, then swings slightly to the right, and picks slightly when closing the pen. Pick it up slightly when drawing a pen. The whole glyph gradually changed from slightly rectangular to slightly oblate. The appearance of this writing shows that the official script has developed from ancient times to Han Li, and it has matured. This development was completed in the Eastern Han Dynasty.
If in doubt, please ask.