Because the ISBN systems was already in place internationally when the EAN 13 system was adopted, the book industry was allocated the prefix 978 as a generic code for use on books regardless of their country of origin. The final digit of the EAN number is a check digit derived from a calculation of the previous twelve digits. If you are using a film master supplier then you simply give them the ISBN and let them perform the complicated calculation. They will have software to do this and check the result. The EAN 13 system is a cross-industry standard used in all countries other than USA and Canada, where a similar and compatible system known as UPC is used in most trades.
Most scanners are able to read both barcodes.
The UPC codes are not, however, able to include the entire ISBN and the price-point version of the code, used on mass market paperbacks identifies the book simply by publisher and price category. Yes, but not on the same surface. In order to avoid confusion at the point of scanning, it is essential that the correct barcode is scanned. It is, therefore, unacceptable to have more than one barcode on the outside of a product. This only really causes problems in North America where both UPC and EAN barcodes may be required by different markets for the same article.