If a card is discarded but is moved to a hidden zone, how are its characteristics determined?

When a card is discarded and then moved to a hidden zone, its characteristics are considered undefined. This is because, once a card is no longer in a public zone, specific details about it become inaccessible. In Magic: The Gathering, hidden zones such as the graveyard or exile do not allow for players to view the characteristics of the cards within them unless specific effects allow otherwise, such as a card that allows a player to view a card in exile or the graveyard.

The idea of characteristics being "undefined" means that while the card is in this hidden zone, its abilities, power, toughness, or any other defining traits cannot be assessed or referenced until the card is brought back to a public zone where those characteristics can be determined again.

This context allows for clarity on how cards interact within the game and emphasizes the importance of zones and visibility in determining card behavior. Thus, the characteristics do not remain the same, cannot be assessed after showing the card, and are not necessarily set to zero. They remain undefined until the card is in a zone where its properties can be acknowledged.