OK for motherboard to be in direct contact with the bottom of the case?

Is it OK for the bottom of the motherboard to be in direct contact with case? I didn’t realize XL-ATX meant the board was actually Longer (I thought it stood for “Extra…

OK for motherboard to be in direct contact with the bottom of the case?

Source: [H]ardOCP – OK for motherboard to be in direct contact with the bottom of the case?