# EPUBCheck HTM-011: Entity is undeclared

Source: https://epublab.com/epubcheck/htm-011/ (updated 2026-11-03)

EPUBCheck HTM-011 is an error message: “Entity is undeclared.” A named entity is used that the document does not declare; XML only knows &, <, >, " and '.

- Official message (EPUBCheck 5.4.0): Entity is undeclared.
- Default severity: Error
- EPUBCheck's suggestion: Define the entity or use the numbered entity instead.

## Typical causes

- HTML entities such as  , — or © in XHTML.

## How to fix it

- Use numeric references (  for a non-breaking space, — for an em dash) or type the character itself in UTF-8.

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