Some books published in East Asia and Middle East are bound at the right side, not the left side as western publications. The barcode shouldn’t be placed (on the place) as usual at what would be the front of the item bound at the right side.
Regardless of the fact that the orientation of the text of these items is right to left, the barcode must be placed on what would be the inside front cover of what would be the "western" orientation of the physical item or at the back of items bound right to left.
Center the label horizontally with the top edge ½ inch down from the edge of the page. If there is information there that is identical to info on the opposite cover then you may place barcode over that information. Otherwise, place it on the next available page on the right side.
This is to facilitate the item being scanned on self checkout machines.