People who used to practice calligraphy had to "tick" before "tracing", that is, "double hook", and then "fill in". Now the book of tracing the red gives us a "double hook", only "filling", that is, tracing the red, that is, beginners draw with a brush along the handwriting on the printed red copybook, which speeds up the learning progress.
"Imitation" refers to copying, that is, covering the model characters with transparent paper (Sydney paper, moisture-proof paper, cotton paper and sulfuric acid paper), and then covering thinner and more transparent historical paper and Xuan paper (flowers, cotton wool and single propaganda) on the transparent paper, and writing one by one along the shadows of the characters on the paper.
The role of transparent paper (Sydney paper, moisture-proof paper, cotton paper and sulfuric acid paper) is to prevent ink from polluting copybooks after penetrating historical paper or rice paper. Because there are two layers of paper on the copybook, the words on the copybook are vague, so the ancients put another copybook in front and carefully observed the font.