Semantics: the branch of linguistics and logic concerned with meaning. There are a number of branches and subbranches of semantics, including formal semantics, which studies the logical aspects of meaning, such as sense, reference, implication, and logical form, lexical semantics, which studies word meanings and word relations, and conceptual semantics, which studies the cognitive structure of meaning.
Not the US Constitution, however the War Powers Resolution of 1973 (50 U.S.C. 1541-1548) is Federal Law of the United States, and acknowledged by the UN Security Council. The United States Constitution creates the Separation of Powers as well as the mechanisms for the Legislative Branch to enact new laws, which themselves become part of the United States Code. In this case, the Legislative Branch wanted the law, the Executive (Nixon) vetoed it, and was then overridden by a 2/3 vote in both Legislative Houses at which point it became law.
There is a clear distinction between a "Declaration of War", the use of an "Authorization of Military Force" provision by Congress, or simply "Going to War", as is possible without Congressional Approval under the War Powers Resolution of 1973.
Under the War Powers Resolution of 1973, the President can commit our Armed Forces to any act that seen fit without authorization from Congress in the form of an Authorization of Military Force or a formal Declaration of War with the following restrictions placed on it:
- the President must notify Congress within 48 hours of committing armed forces to military action.
- armed forces are forbidden from remaining for more than 60 days + a 30 day withdrawal period.