Complex sentence: In this example, the values are all literal values, but these could also be foreign keys to pre-defined value lists; these are particularly useful when the possible values are known to be limited (i.e., enumerable).
Split into simpler sentences: In this example, the values are all literal values, but they could also be pre-defined value lists. The latter are particularly useful when the possible values are known to be limited (i.e., enumerable).