What does the tick tool mean in three-level hard pen calligraphy?

In the three-level hard pen calligraphy, the inspection tool usually refers to the hard pen calligraphy practice paper printed with Mi Zige.

Using this exercise paper can help learners better master the structure and stroke layout of Chinese characters. Mi Zige's lines can help to determine where the strokes of each Chinese character should be placed and the relative positional relationship between the strokes. This helps to improve learners' calligraphy level and make their calligraphy more standardized and tidy.