What is EPUB 2.0 Metadata "dc:identifier" Element?

EPUB 2.0 Metadata "dc:identifier" is a required metadata element to specify a code that uniquely identifies the EPUB 2.0 book.

To use "dc:identifier" properly, you need to meet the following two requirements:

1. <package unique-identifier="book-id"> - Specifies an XML element id like "book-id" to refer to the <dc:identifier> metadata element in the package.opf file.

2. <dc:identifier id="book-id">...</identifier> - Specifies the actual code that uniquely identifies the EPUB 2.0 book.

There are a number of ways to provide the identification code:

• Create your own code like. For example: "fyicenter-com-row-your-boat".
• Use the URI of the book. For example: "http://dev.fyicenter.com/EPUB/Row-Your-Boat".
• Use the ISBN number of book, if you have one. For example: "urn:isbn:978-3-16-148410-0".
• Generate a UUID for your book at https://www.uuidgenerator.net/. For example: "urn:uuid:404d6d3a-429e-11e8-842f-0ed5f89f718b".

EPUB 2.0.1 specification adds one attribute, "scheme", to the "Dublin Core Metadata Element Set" standard on this "dc:date" element:

• opf:scheme - to specify the system name or authority name who generates this identification value. For example, scheme="ISBN" specifies an ISBN (International Standard Book Number) identification number.

If you want to see an example of "dc:identifier" metadata, you can download this EPUB 2.0 book, Row-Your-Boat-2.0.epub. Unzip it and open package.opf. You see the "dc:identifier" metadata element:

<package xmlns="http://www.idpf.org/2007/opf" version="2.0" 
  unique-identifier="book-id">
  <metadata xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:opf="http://www.idpf.org/2007/opf">
    <dc:title>Row, Row, Row Your Boat</dc:title>
    <dc:identifier id="book-id" opf:scheme="ISBN">123456789X</dc:identifier>
    ...

⇒ EPUB 2.0 Metadata - dc:title Element

⇐ What Is EPUB 2.0 Package Metadata

⇑ EPUB 2.0 Package Metadata

⇑⇑ EPUB FAQ and Tutorials