There are a couple of add-ons that allow the saving of these details externally, more for back-up or external editing, rather than the use you suggest. But they are one small step in that direction.
Because the field is important to the card’s (or note’s) information, how would you propose using an external file that is card-specific or note-specific? It seems like there could potentially be as many of these external files as there are cards in a deck.