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EPUBCheck · Images, audio and media overlays

EPUBCheck MED_013: overlay never cites chapter

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EPUBCheck MED_013 is an error message: “Media Overlay Document referenced from the "media-overlay" attribute does not contain a reference to this Content Document.” A chapter's media-overlay attribute names a SMIL file that never refers to that chapter. The overlay must contain text elements pointing to the chapter it narrates, otherwise the reading app has nothing to synchronise.

The official message

Media Overlay Document referenced from the "media-overlay" attribute does not contain a reference to this Content Document.

Default severity
Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
EPUBCheck version
5.4.0

EPUBCheck prints this ID with an underscore instead of a hyphen; this page uses the ID exactly as EPUBCheck reports it.

Typical causes

  • The media-overlay attribute set on the wrong manifest item.
  • A SMIL file whose text src paths still point to old file names.

How to fix it

  1. Open the SMIL file named by the attribute and check the src of its text elements.
  2. Correct the paths so they point to the chapter, or set the attribute to the overlay that really narrates it.
  3. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

When it's not this

If the overlay refers to the chapter but the attribute names another overlay, see MED_012.

Terms used here

Other MED messages

  • MED_012 The "media-overlay" attribute does not match the ID of the Media Overlay that refers to this document.
  • MED_014 Media overlay audio file URLs must not have a fragment, but found '#…'.
  • MED_011 EPUB Content Document referenced from multiple Media Overlay Documents.
  • MED_015 Media overlay text references must be in reading order. Text target "…" is before the previous link target in … order.
  • MED_010 EPUB Content Documents referenced from a Media Overlay must specify the "media-overlay" attribute.
  • MED_016 Media Overlays total duration should be the sum of the durations of all Media Overlays documents.

Sources

Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EpubCC.

FAQ

What does EPUBCheck MED_013 mean?

EPUBCheck MED_013 is an error message: “Media Overlay Document referenced from the "media-overlay" attribute does not contain a reference to this Content Document.” A chapter's media-overlay attribute names a SMIL file that never refers to that chapter. The overlay must contain text elements pointing to the chapter it narrates, otherwise the reading app has nothing to synchronise.

Is MED_013 an error?

MED_013 is reported as error by default. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.