I must know this for my cities that are upcoming. Is Base Set DCE legal in modified format, or do I need an outside reference to use it? Also, here is the card if you need the exact wording.
A reference for an older card is only required if it creates a significant change in how the card effect is carried out.
In both cases, DCE is always a Special Energy card that provides {C}{C} and nothing else. It's like that in both printings; therefore no ref is required.