ಟೆಂಪ್ಲೇಟ್:Infobox book/isbn
This subtemplate is used by {{infobox book}} and {{infobox graphic novel}} to automatically generate links to Special:Booksources. If the input consists of only digits, hyphens, and Xs, then this subtemplate will link to Special:Booksources and use Module:Check isxn to validate the ISBN. If the ISBN is not valid, this subtemplate will still generate the link, but will add the transclusion to Category:CS1 errors: ISBN/Category:Pages using infobox book with an invalid isbn and generate an error message. However, if the input is not purely digits, hyphens, and Xs, no linking is performed, and it simply returns the input and adds Category:Pages using infobox book with an invalid isbn (suppressed in template space). This could be made more advanced.
Examples
{{Infobox book/isbn|0-9752298-0-X}}
→ 0-9752298-0-X{{Infobox book/isbn|ISBN 0-9752298-0-X}}
→ ISBN 0-9752298-0-X{{Infobox book/isbn|garbage}}
→ garbage