Compound noun phrase. This is one or more noun phrases connected with 'of', as in "piece of paper". The part after the 'of' is another compound noun phrase.

Note that this general rule does not allow the noun phrase after the 'of' to be qualified with an article or number, except that we make an exception to allow a definite article. Other cases ("a piece of four papers") do not generally make sense, so we won't attempt to support them; instead, games can add as special cases new nounPhrase rules for specific literal sequences where more complex grammar is necessary.

grammar compoundNounPhrase(simple) :   NounPhraseWithVocab