This Counter64 counts packets dropped on this ATM interface's transmit path due to errors, specifically noting buffer operation failures and invalid protocol types as causes. An admin watches this for a rising count that would indicate a resource or protocol problem on the transmit side of the port itself, distinct from congestion. For example, a sudden jump in csAtmInterfaceConfTransmitErrors alongside other buffer-related counters would point the admin toward a transmit buffer exhaustion issue on that interface.