"Don't delete" notation (4)
I believe the answer is:
stet
(Other definitions for stet that I've seen before include "Notation meaning leave as is, don't alter spelling" , "Proofreader's mark that the original text should be kept" , "Editing instruction that matter marked for deletion is to be retained" , "(On proofs) instruction to cancel a correction" , "indicates second thoughts are not always better" .)