Except for red, pens of other colors have no special meaning for others to write. People are afraid to write with a red pen, which has been an established tradition for thousands of years. It is taboo to write with a red pen, and it is even more taboo to accept what is written with a red pen. Relevant basis:

1, there is a folk saying that "Dan Shu is ominous". As we all know, in ancient times, except for people sitting in the golden palace, calligraphy was generally used by yamen to record the names of criminals. There is a folk saying that Yan Yan crossed the book of life and death with a brush, and those who were crossed out by calligraphy were undoubtedly sentenced to death. Up to now, criminals who have been sentenced to death have marked their names with an "X" or "√" in red ink.

2. Because some people feel guilty because they write with a red pen, which leads to friends breaking up, there is also a saying that writing with a red pen is breaking up.