# What is dcterms:modified?

Source: https://epubcc.com/glossary/dcterms-modified/ (updated 2026-11-04)

dcterms:modified is the required last-modified date of an EPUB 3, written in the package document as a meta element. EPUB 3.3 requires exactly one, in the form YYYY-MM-DDThh:mm:ssZ (UTC).

## Why it matters when you convert a PDF to EPUB

It is one of the four pieces of metadata every EPUB 3 must have, with dc:identifier, dc:title and dc:language, and it is the one most often forgotten in hand-made or edited files. A missing or malformed value makes the whole EPUB invalid, which is enough for a store or Send to Kindle to reject it.

A missing dcterms:modified shows up in EPUBCheck as a schema error on the package document (RSC-005), and a date in the wrong format as a date syntax message (OPF-053 or OPF-054).

How EpubCC handles it: the package document always carries dcterms:modified set to the moment of the conversion, in UTC and in exactly the format the specification asks for.

**Is dcterms:modified the publication date?** No. It is when the EPUB file was last changed. The publication date of the work goes in dc:date.