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EPUBCheck · Package document (OPF)

OPF-053

Updated:

EPUBCheck OPF-053 is a warning message: “Date value "…" does not follow recommended syntax as per http://www.w3.org/TR/NOTE-datetime:….” A date in the metadata does not follow the recommended format (W3C date and time), so some apps may not read it.

The official message

Date value "%1$s" does not follow recommended syntax as per http://www.w3.org/TR/NOTE-datetime:%2$s.

Default severity
Warning. The EPUB is still valid, but something is likely to cause problems in some reading apps. EPUBCheck exits with 0 unless you pass --failonwarnings.
EPUBCheck version
5.4.0

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

Typical causes

  • Dates written as text or in local formats, such as "March 2020" or "03/15/2020".

How to fix it

  • Write the date as YYYY, YYYY-MM or YYYY-MM-DD, for example 2020-03-15.

Terms used here

Other OPF messages

  • OPF-054 Date value "…" is not valid as per http://www.w3.org/TR/NOTE-datetime:….
  • OPF-050 TOC attribute references resource with non-NCX mime type; "application/x-dtbncx+xml" is expected.
  • OPF-049 Item id "…" was not found in the manifest.
  • OPF-048 Package tag is missing its required unique-identifier attribute and value.
  • OPF-060 Duplicate entry in the ZIP file: "…" (file names must be unique after Unicode canonical normalization and full case folding).

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

FAQ

What does EPUBCheck OPF-053 mean?

EPUBCheck OPF-053 is a warning message: “Date value "…" does not follow recommended syntax as per http://www.w3.org/TR/NOTE-datetime:….” A date in the metadata does not follow the recommended format (W3C date and time), so some apps may not read it.

Is OPF-053 an error?

OPF-053 is reported as warning by default. The EPUB is still valid, but something is likely to cause problems in some reading apps. EPUBCheck exits with 0 unless you pass --failonwarnings.