Comment by dredmorbius

For those unfamiliar with terms:

"Black Letter Law":

In common law legal systems, black-letter law refers to well-established legal rules that are no longer subject to reasonable dispute.[1] Black-letter law can be contrasted with legal theory or unsettled legal issues.

<https://en.wikipedia.org/wiki/Black-letter_law>

Searching for black letter and combat turns up:

International Institute of Humanitarian Law: The Manual on the Law of Non-International Armed Conflict With Commentary (2006)

Among definitions:

For the purposes of this Manual, fighters are members of armed forces and dissident armed forces or other organized armed groups, or taking an active (direct) part in hostilities.

(p. 4)

Civilians are all those who are not fighters.

(p. 5)

Military objectives are objects which by their nature, location, purpose, or use make an effective contribution to military action and whose total or partial destruction, capture, or neutralisation, in the circumstances at the time, offers a definite military advantage.

(p. 5)

<https://www.humanrightsvoices.org/assets/attachments/documen...>

(I'll note that one of the co-authors is affiliated with Tel Aviv University in Israel, though others do not appear to be Israeli.)

The US DoD publishes a law of war manual, last updated in 2023:

<https://media.defense.gov/2023/Jul/31/2003271432/-1/-1/0/DOD...>