The keyword phrase "september 11th hsr" functions grammatically as a noun phrase. In this construction, the core component "hsr" serves as the head noun, which is the main element of the phrase. The term "September 11th" acts as a modifier, specifying the context or type of "hsr".
A detailed analysis of the phrase's components clarifies this structure. "HSR" is an acronym, presumably standing for a noun such as "Homeland Security Research," "Health Services Research," or a specific report or project title. The preceding term, "September 11th," functions as a noun adjunct (a noun used to modify another noun). It is not an adjective in the traditional sense but provides a specific thematic or temporal classification for the head noun "hsr." For example, if "hsr" stands for "report," the phrase identifies a specific report about or related to the events of September 11th.
For the purpose of an article, treating "september 11th hsr" as a cohesive noun phrase is the correct approach. This allows the term to function as the subject or object of a sentence, establishing it as the central topic of discussion. The main point of the keyword is therefore a specific concept, entity, or field of study (the "hsr") that is directly qualified by its relationship to September 11th.
