The keyword "11 sept 2001" functions grammatically as a proper noun. As a specific and unique date, it names a particular point in time, much like a proper noun names a specific person or place. It operates as a single conceptual unit within a sentence.
While its primary part of speech is a noun, it also frequently serves as a noun adjunct or an adjectival phrase. In this capacity, it modifies another noun by providing specificity. For example, in the phrase "the post-11 sept 2001 era," the date functions adjectivally to describe the "era." When used as a noun, it can be the subject of a sentence (e.g., "That date changed global politics.") or the object of a verb or preposition (e.g., "The world remembers that day.").
Determining its role is crucial because it dictates the focus of the sentence. Using the term as a noun centers the narrative on the event of the day itself. Using it as an adjectival modifier shifts the focus to the consequences, policies, or concepts that are defined by the event. The author's choice between these two grammatical functions directly controls the narrative emphasis.
