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EPUBCheck · XHTML content documents

EPUBCheck HTM_060b: viewport that will be ignored

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EPUBCheck HTM_060b is a usage message: “EPUB reading systems must ignore viewport meta elements in reflowable documents; viewport declaration "…" will be ignored.” A viewport meta element will be ignored by reading apps, so it has no effect. EPUBCheck reports this usage note in two cases. HTM_060b is a viewport in a reflowable document, where reading apps must ignore it. HTM_060a is a second (or later) viewport in a fixed-layout document, where only the first one counts.

The official message

EPUB reading systems must ignore viewport meta elements in reflowable documents; viewport declaration "%1$s" will be ignored.

Default severity
Usage. Informative only and hidden by default: it appears when EPUBCheck runs with -u (--usage). It does not make the EPUB invalid.
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.

%1$s, %2$s… are filled in with the file, value or element EPUBCheck found.

Typical causes

  • Head content copied from web pages, which usually carry width=device-width, into reflowable chapters (HTM_060b).
  • Fixed-layout templates reused for reflowable chapters (HTM_060b).
  • Duplicated head content in a fixed-layout page, leaving two viewport elements (HTM_060a).

How to fix it

  1. Open the file EPUBCheck names (the message gives the path, line and column) in a text or EPUB editor such as Sigil, or unzip the EPUB and open it there.
  2. In a reflowable document, remove the viewport meta element: it does nothing there.
  3. In a fixed-layout document, keep only the first viewport meta element, with both width and height, and remove the others.
  4. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

When it's not this

If a single viewport repeats width or height inside its content attribute, that is HTM_059.

Also reported as

  • HTM_060a (usage): EPUB reading systems must ignore secondary viewport meta elements in fixed-layout documents; viewport declaration "%1$s" will be ignored.

Terms used here

Other HTM messages

  • HTM_059 Viewport "…" property must not be defined more than once, but found values […].
  • HTM_061 "…" is not a valid custom data attribute (it must have at least one character after the hyphen, be XML-compatible, and not contain ASCII uppercase letters).
  • HTM_058 HTML documents must be encoded in UTF-8, but UTF-16 was detected.
  • HTM_062 SVG "xlink:href" attribute is deprecated; an "href" attribute should be used instead.
  • HTM_057 Viewport "…" value must be a positive number or the keyword "device-…"
  • HTM_056 Viewport metadata has no "…" dimension (both "width" and "height" properties are required)

Sources

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

FAQ

What does EPUBCheck HTM_060b mean?

EPUBCheck HTM_060b is a usage message: “EPUB reading systems must ignore viewport meta elements in reflowable documents; viewport declaration "…" will be ignored.” A viewport meta element will be ignored by reading apps, so it has no effect. EPUBCheck reports this usage note in two cases. HTM_060b is a viewport in a reflowable document, where reading apps must ignore it. HTM_060a is a second (or later) viewport in a fixed-layout document, where only the first one counts.

Is HTM_060b an error?

HTM_060b is reported as usage by default. Informative only and hidden by default: it appears when EPUBCheck runs with -u (--usage). It does not make the EPUB invalid.