HTM_055 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.

EPUBCheck · XHTML content documents

`HTM_055`

Updated: Nov 3, 2026

EPUBCheck HTM_055 is a usage message: “The "…" element should not be used (discouraged construct).” The document uses an HTML element that EPUB discourages because reading apps support it poorly; EPUBCheck names the element.

The official message

The "%1$s" element should not be used (discouraged construct)

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

Elements carried over from web pages.

How to fix it

Replace the element with a better-supported alternative or remove it.

Terms used here

What is XHTML in EPUB?

Other HTM messages

HTM_057 Viewport "…" value must be a positive number or the keyword "device-…"
HTM_060a EPUB reading systems must ignore secondary viewport meta elements in fixed-layout documents; viewport declaration "…" will be ignored.
HTM_060b EPUB reading systems must ignore viewport meta elements in reflowable documents; viewport declaration "…" will be ignored.
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-048 SVG Fixed-Layout Documents must have a "viewBox" attribute (on the outermost "svg" element).
HTM_062 SVG "xlink:href" attribute is deprecated; an "href" attribute should be used instead.

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