I have a question regarding attributive nouns, or noun-noun compounds, and how they are integrated into syntactic rules for NP formation. Typically, the rule given in textbooks for forming a NP is the following:
NP --> (D)(AdjP+) N (PP+)
However, I am trying to figure out how the noun-noun compounds can fit into this. Examples of these include "chocolate chip cookie dough", where "chocolate chip" and "cookie" are both nouns, but here are acting adjective-like in how they modify "dough". More examples include "grandfather clock", "coffee break", and "polka dot sweater". However, it feels wrong to simply call these all adjectives. How do we go about integrating these (what I consider NPs) into the NP rule? Would they act as adjuncts, just like adjectives do when modifying a noun (so NP --> (D)(AdjP+)(NP+) N (PP+))? Any help on this problem would be GREATLY appreciated!