Anaphora (linguistics) - Zero Anaphora

Another form of anaphora, similar to a pro-drop is the zero anaphora. For example:

There are two roads to eternity, a straight and narrow, and a broad and crooked.

The gap in the phrase "a straight and narrow " is the anaphor for the antecedent "two roads to eternity"; the two phrases are said to have a zero-anaphoric relationship. Similarly, the phrase "a broad and crooked " contains another gap anaphor.

Zero anaphora is far more prevalent (and studied) in Chinese and Japanese.