The keyword phrase functions grammatically as a noun phrase. The core or head of the phrase is the noun "date," which is modified by the adjective "due" and specified by the preceding date, "September 11, 2025." Therefore, the main point of the keyword is a specific, identifiable concept or thing: a deadline.
In this construction, "due date" operates as a compound noun, signifying a deadline. The date "September 11, 2025," itself a noun phrase, acts as an adjectival specifier, pinpointing the exact deadline being referenced. The entire phrase does not contain a verb and does not express a complete thought, but rather names a single, concrete temporal milestone. Its function is to identify a specific subject, not to describe an action or a state of being.
Understanding this term as a noun phrase is crucial because it dictates that the article's primary subject is the deadline itself. The focus should be on defining or elaborating upon this event: its significance, the requirements associated with it, the context surrounding it, or the implications of this specific date. The article is thus positioned to explain a 'what' (the specific deadline) rather than a 'how' or 'why'.
