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EPUBCheck · Obsolete features

OBS-001

Updated:

EPUBCheck OBS-001 is a usage message: “Usage of … is outdated.” The EPUB uses a feature that still works but is outdated, such as an NCX, font obfuscation, a prefixed CSS property or a deprecated element; the message names it.

The official message

Usage of %1$s is outdated.

Variants

  • content-fallback: manifest content fallback (for resource "%1$s")
  • font-obfuscation: font obfuscation
  • element: the %1$s element
  • ncx: OPF 2 NCX navigation
  • property: the "%1$s" property
  • css-prefixed-property: the CSS prefixed property "%1$s"
  • css-prefixed-value: the CSS prefixed value "%1$s"
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

  • Books made for EPUB 2 or older reading systems, or CSS with vendor prefixes such as -webkit-.

How to fix it

  • Nothing breaks today. When you next update the book, replace the feature with its current equivalent (for example, unprefixed CSS properties).

Terms used here

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

FAQ

What does EPUBCheck OBS-001 mean?

EPUBCheck OBS-001 is a usage message: “Usage of … is outdated.” The EPUB uses a feature that still works but is outdated, such as an NCX, font obfuscation, a prefixed CSS property or a deprecated element; the message names it.

Is OBS-001 an error?

OBS-001 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.