original passage: In the ATA standard, pin 20 is defined as a mechanical key and is not used. This pin's socket on the female connector is often obstructed, requiring pin 20 to be omitted from the male cable or drive connector; it is thus impossible to plug it in the wrong way round.
original sentence: This pin's socket on the female connector is often obstructed, requiring pin 20 to be omitted from the male cable or drive connector; it is thus impossible to plug it in the wrong way round.
sentence2: When these connectors are manufactured, is it likely that a kind of textured surface is added to one side (as is common on USB plugs) to alert the user to which way around they must be held when inserting?
sentence1: In the ATA standard, pin 20 is defined as a mechanical key and is not used. An obstruction is often added to the socket for this pin on the female connector, which means that the male connector cannot include pin 20; this ensures that the plug cannot be inserted the wrong way around.