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EPUBCheck · XHTML content documents

HTM-010

Updated:

EPUBCheck HTM-010 is a usage message: “Namespace "…" is unusual for the prefix "epub".” The epub prefix is bound to an unexpected namespace, so epub:type and other epub attributes may be ignored.

The official message

Namespace "%1$s" is unusual for the prefix "epub".

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

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

Typical causes

  • A typo in the namespace declaration.

How to fix it

  • Declare it as xmlns:epub="http://www.idpf.org/2007/ops" on the html element.

Terms used here

Other HTM messages

  • HTM-009 The DOCTYPE provided is obsolete or irregular and can be removed.
  • HTM-011 Entity is undeclared.
  • HTM-004 Irregular DOCTYPE: found "…", expected "…".
  • HTM-003 External entities are not allowed in EPUB v3 documents. External entity declaration found: ….
  • HTM-025 Non-registered URI scheme type found in href.
  • HTM-045 Encountered empty href.

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

FAQ

What does EPUBCheck HTM-010 mean?

EPUBCheck HTM-010 is a usage message: “Namespace "…" is unusual for the prefix "epub".” The epub prefix is bound to an unexpected namespace, so epub:type and other epub attributes may be ignored.

Is HTM-010 an error?

HTM-010 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.