Template:PublicationFields:ISBN

• ISBN - Enter the publication's ISBN (International Standard Book Number) if it has one. ISBNs were introduced in the late 1960s and have been universally used for paper-based publications since the 1970s. Some electronic and audio publications use them and some don't.
  • ISBN-10 vs. ISBN-13: Prior to 2007 all ISBNs were 10 characters long; the first 9 characters were digits and the 10th, the checksum character, was either a digit or an "X". Around 2007 ISBNs were expanded to 13 digits by adding a 3-digit prefix (978 or 979); the last character is still the ISBN's checksum, but, unlike with ISBN-10s, it's always a digit. Some books printed during the transition period around 2007 included both the 10 digit version and the 13 digit version of the ISBN. The ISFDB software supports both formats, so if two forms of ISBN are present, you can enter either one in this field and document the other one in the Notes field.
  • Hyphens and Spaces: You may enter the ISBN with or without hyphens. Any hyphens or spaces in the entered value will be automatically stripped by the software and the value will be stored in the database without them. If the ISBN is valid, then the ISFDB software will display it with hyphens using the International ISBN Agency's hyphenation rules adjusted for known exceptions like Tor prior to 2007.
  • Checksum Character: Most ISBN-10s whose checksum character is "X" use the uppercase form of the letter "x", but a few use the lowercase form. The ISFDB software automatically converts lowercase "x"'s to uppercase at data entry time, so you can enter either "x" or "X".
  • Embedded Price: If the stated ISBN is of the form "0-586-06604-7-275", do not enter the last hyphen and the three digits that follow it. They indicate the publication's list price and are not part of the ISBN.
  • SBNs: Some English language books published during the late 1960s and 1970s used nine digit "SBN"s without a leading zero. When entering these publications, add the leading zero.
  • Discrepancies between the Stated ISBN and the Entered ISBN: If you entered a value that was not exactly as stated in the publication, e.g. you added a leading 0 to an SBN, explain the details in the Notes field.
  • ISSNs: Magazine ISSNs should not be entered in this field. This is because ISSNs identify the magazine as a whole rather than a particular issue. If an ISSN is present, you can enter it in the Notes field of the series that this magazine issue belongs to.
  • Multiple ISBNs: If a publication has more than one ISBN, then enter one in the ISBN field and enter the other(s) in the Notes field.
  • ISBNs with invalid format: Stated values that may look like ISBNs but do not follow the standard ISBN format, i.e.:
    • 9 digits followed by a digit or an "X"
    • 13 digits starting with 978 or 979
  • are not considered ISBNs for ISFDB purposes. They will generate a "Bad Format" yellow warning on post-submission pages. Do not enter them in the ISBN field; document them in Notes instead.
  • ISBNs with an invalid checksum: An ISBN that follows the standard ISBN format but fails checksum validation will generate a "Bad Checksum" yellow warning on post-submission pages. After double-checking that the ISBN was entered as it appears in the publication, it should be entered in the ISBN field. The fact that it fails checksum validation should be documented in the Notes field.