Skip to content
EPUBCheck · Package document (OPF)

EPUBCheck OPF-073: DOCTYPE identifier not allowed

Updated:

EPUBCheck OPF-073 is an error message: “External identifiers must not appear in the document type declaration.” An XML document's DOCTYPE uses an external identifier (a public or system id) that EPUB does not allow for that media type. EPUB only permits a short list, such as the SVG 1.1, MathML 3.0 and NCX DTDs.

The official message

External identifiers must not appear in the document type declaration.

Default severity
Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
EPUBCheck version
5.4.0

Typical causes

  • An XHTML chapter in an EPUB 3 with an XHTML 1.1 or XHTML 1.0 DOCTYPE carried over from EPUB 2.
  • An SVG file exported with a DOCTYPE for another SVG version.
  • A DOCTYPE copied from a web page template.

How to fix it

  1. Open the file EPUBCheck points to and look at its DOCTYPE line.
  2. For EPUB 3 XHTML, use <!DOCTYPE html> or no DOCTYPE at all.
  3. For other files, use the identifier listed for their media type in EPUB 3.3, or remove the DOCTYPE.

When it's not this

If the XHTML DOCTYPE is merely obsolete, EPUBCheck reports HTM-004 instead.

Terms used here

Other OPF messages

  • OPF-072 Metadata element "…" is empty.
  • OPF-074 Package resource "…" is declared in several manifest items.
  • OPF-070 Custom collection role "…" is an invalid URL.
  • OPF-067 The resource "…" must not be listed both as a "link" element in the package metadata and as a manifest item.
  • OPF-066 Missing "dc:source" or "source-of" pagination metadata. The pagination source must be identified using the "dc:source" and "source-of" properties when the content includes page break markers.

Sources

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

FAQ

What does EPUBCheck OPF-073 mean?

EPUBCheck OPF-073 is an error message: “External identifiers must not appear in the document type declaration.” An XML document's DOCTYPE uses an external identifier (a public or system id) that EPUB does not allow for that media type. EPUB only permits a short list, such as the SVG 1.1, MathML 3.0 and NCX DTDs.

Is OPF-073 an error?

OPF-073 is reported as error by default. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.

PDF to EPUB tools

Every tool uses the same engine and starts with a free 5-page sample.