?

? usually signals an unknown ATK, DEF or Level value.

If a monster's ATK or DEF is represented as a '?' on the card, it cannot be searched from the Deck using the relevant value, since it does not have a value whilst in the Deck.

If a monster has ? ATK or DEF and the effects that determines the ATK or DEF cannot be activatd or are negated while on the field, its ATK or DEF is treated as 0.