The keyword phrase "11 de sep estados unidos" functions as a proper noun. It acts as a single nominal unit that names a specific, singular historical event: the September 11th attacks in the United States.
This classification is derived from the composition of the phrase. "Estados Unidos" (United States) is a proper noun, and "11 de sep" (September 11th) acts as an adjectival modifier specifying the date. When combined, they form a compound proper noun, similar to "the French Revolution" or "the Cold War." The phrase does not describe an action (verb) or a quality (adjective) but rather names a distinct entitythe event itself.
Recognizing the phrase as a proper noun is essential because it establishes the subject of the article as a specific, well-defined historical event. This dictates that the content should focus on factual details, context, and the impact related to that singular occurrence, rather than abstract concepts. It is the central subject around which all related facts, analyses, and discussions will be built.
