Is it legal to mark the front of sideboard cards or sleeves to make it easier to identify and remove them when resetting the deck between practice games?

Ruling: Marking the front of cards or sleeves is legal and does not violate marked cards rules, as it does not provide information about card location from the back of the cards or affect shuffling.

Nuances:

• While technically legal, there is a risk that marking material (like sharpie) could potentially rub off onto the back of other cards, which would then create an illegal marked cards situation and could result in disqualification
• The practical concern is that even though front-marking doesn't create an advantage during gameplay, the transfer of marks to card backs creates enforcement risk