As indicated below, the binding must be taken into account when designing the file for a Wire-O Bound Book. On the top, bottom, and non-spine edges, the margin should be a minimum of 0.25". On the binding edge, 0.27" of margin for the binding plus 0.25" of safety will ensure both that nothing gets cut off, and that the content looks centred.
Even though it will actually be slightly off centre, the reader will judge from the edge of the bindery punches rather than the actual spine edge of the sheet. Therefore it is always important to include the margin for binding in any margin calculations, in case more margin than the recommended minimum is desired. If, for example, a 0.5" margin is...