Xu Shen divided many Chinese characters into 540 parts according to their physical structure, and created a systematic "radical spelling". How are these 540 films arranged? According to Xu in Shuo Wen Jie Zi, it means "starting a career", "finishing a career" and "miscellaneous but not excessive, universal but not formal". The 540 films are arranged according to "beginning and end", showing Xu Shen's philosophical thoughts. This is the fashion of the times, so there is no need to criticize the ancients. "Associating according to shape" refers to arranging the order according to the similarity of glyphs.