marginalia
/ˌmɑr.dʒɪˈneɪl.i.ə/Definitions
1. noun
notes or comments written in the margins of a book, document, or other written work.
“The professor’s marginalia on the student’s essay revealed her thoughtful feedback.”
2. noun
minor or unimportant details.
“The manager focused on the marginalia of the company’s financial reports.”