What does writing with a red pen mean?

In ancient times, people sentenced to death would write their names on gambling numbers with chicken blood. Later, it evolved into writing in red letters, so the yamen used red pens to record the names of criminals. Writing a letter in red also means declaring war on the other side.

So even now, in addition to the teacher correcting papers and the accountant correcting them, it is rare to record matters in red ink. Especially the names of people, writing in red is a big taboo.