Authors of electronic material should give preference to publications that are archived and curated in trusted online digital repositories, e.g., an ISO-certified repository. Digital repositories ideally should be in more than one country, preferably on different continents. Publication electronically in Portable Document Format (PDF) should comply with the PDF/A archival standard. An electronic publication must not be altered after it is published. Any such alterations are not themselves considered published. Corrections or revisions must be issued separately to be considered published. The publication date for names established under this code is the date on which a publication, as defined in Article 4, first becomes available either in print or online. In the absence of proof establishing some other date, the one appearing in the publication itself must be accepted as correct.