The bar code on the book is ISBN code. The previous ISBN code was 10, and the prefix code 978 was in front of the barcode. Now the two codes have been unified, and the ISBN code is also 13, which is exactly the same as the barcode number. 978 and 979 are special prefix codes assigned to books by ean international. I used to use 978, but now the coding resources based on 978 are running out, so I start to use 979 prefix. The bar code of a book is the book number, which is managed by the Press and Publication Administration (now the State Administration of Press, Publication, Radio, Film and Television). Of course, it cannot be coded at will.