For files like PDFs, there’s no way to place canonical tags while in the web page header mainly because there isn't a site area. In this kind of scenarios, you’ll really need to use HTTP headers to set canonicals. Al enviar este formulario, acepto que PrestaShop S.A utilice los datos https://bookmarklethq.com/story18765179/a-review-of-automatyczne-tagi-hreflang-i-tagi-kanoniczne-seo