"In re" is a legal term that is often abbreviated from the Latin phrase "in rebus" meaning "in the matter of." It is commonly used in legal documents and refers to a court case or a specific matter being discussed. In this context, "in re" can be interpreted as the starting phrase of a memo referring to a specific legal case or matter.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Memo heading. Explanations are generated by AI and may be inaccurate.