noun, noun or participle which takes 'suru'
writing in red ink; red-ink notation
Refers to the act of writing or annotating with red ink, often for corrections, emphasis, or official marks. Can be used as a noun or with する.
先生は答案に朱記を入れた。
The teacher added red-ink markings to the exam paper.
重要な箇所に朱記してください。
Please mark the important parts in red ink.