Book “versions” and book “editions” are not the same thing, and both books and book parts need the ability to name a “<version>” as well as well as an <edition> . The element <content-version> acts for books and book parts as “<article-version>” does for articles. A <content-version> for a book may contain (for example) a word or phrase from a controlled version vocabulary, an uncontrolled version status word (“draft” or “revised proof”), a version statement (“Second revised print version”), or a publisher’s version number (“B-385R5” or “ver. 2.0”).

With the recent increase in availability of early versions of books and book chapters, it is becoming more important to record, within the XML document, a status, version name, version number, lifecycle stage, or similar descriptor. Many publishers are making more than one “version” (ordinary English word) of a document available to the public, for example, making public a proof, then a corrected proof, and then the copy of record. This practice argues in favor of allowing version information as part of the metadata that travels with the XML document rather than treating it as production metadata that is stored externally. This <content-version> element was created to hold that version information. A new version need not change the edition.

The <content-version> element is free form and may contain any content from a complicated version description, to a controlled vocabulary descriptor, to a simple version number. There seems to be little consensus among publishers as to what constitutes a “version” of a book or chapter, and even less agreement concerning how to name (or number or describe) that version. As an example, the JATS Standing Committee (which originally defined this element for JATS) was not even able to reach consensus concerning whether a “proof” is a version, a status, a stage in the publication life-cycle, or something else. Experience indicates that a document might record its version as “Proof”, “copy-edited”, “ITH-12609” or “0.4”.