# EPUBCheck HTM-051: Microdata without RDFa, how to fix it

Source: https://epubcc.com/epubcheck/htm-051/ (updated 2026-11-04)

EPUBCheck HTM-051 is a warning message: “Found Microdata semantic enrichments but no RDFa. EDUPUB recommends using RDFa Lite.” The content uses Microdata but no RDFa, and the EDUPUB profile recommends RDFa Lite. EPUBCheck only reports this when it validates against the EDUPUB profile, set by dc:type metadata or by running it with -profile edupub. It is a warning: the EPUB stays valid.

- Official message (EPUBCheck 5.4.0): Found Microdata semantic enrichments but no RDFa. EDUPUB recommends using RDFa Lite.
- Default severity: Warning

## Typical causes

- An educational book declared as EDUPUB whose semantic markup uses itemscope and itemprop attributes.
- A book validated with -profile edupub by mistake.

## How to fix it

1. If the book is meant to follow EDUPUB, express the same semantics with RDFa Lite attributes (vocab, typeof, property) instead of, or as well as, Microdata.
2. If the book is not an EDUPUB publication, remove the edupub dc:type or run EPUBCheck without -profile edupub.
3. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

## When it's not this

Outside the EDUPUB profile Microdata is allowed in EPUB 3 and this message does not appear.

## Sources

- EPUB 3.3, §6.1.3.2 RDFa: https://www.w3.org/TR/epub-33/#sec-xhtml-rdfa (read 2026-11-04)
- EPUBCheck wiki: Running EPUBCheck (command-line options): https://github.com/w3c/epubcheck/wiki/Running (read 2026-11-04)

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