# EPUBCheck OPF-088: Unrecognized epub:type value …

Source: https://epublab.com/epubcheck/opf-088/ (updated 2026-11-03)

EPUBCheck OPF-088 is a usage message: “Unrecognized epub:type value "…".” An epub:type value is not in the EPUB structural semantics vocabulary, so reading apps will ignore it.

- Official message (EPUBCheck 5.4.0): Unrecognized epub:type value "%1$s".
- Default severity: Usage

## Typical causes

- A misspelling such as "footnotes" on a single note, or a value invented for styling.

## How to fix it

- Use a value from the vocabulary, or give a custom value a declared prefix. Use class for styling.

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