Undefined entities are not reported for EPUB2 checks.

[typopaul]

Non-standard entities, for example &linkref; are not reported when the checked file is EPUB2.
In EPUB3 such entities are reported as errors.

Is there a certain reason for this behavior?

[rdeltour]

If entities are defined in an external DTD, that would be valid in EPUB 2 (but not in EPUB 3).
Could you share a sample file to reproduce the issue?

[typopaul]

@rdeltour

Find attached a zip file with a sample file containing a "wrong" entity in an EPUB2 file and a screenshot from the Thorium Reader.
I understand that the entity should be associated with an external DTD/resource.
I am surprised that the EPUB Checker does not report it as an error but Thorium Reader does.

issue1546_sample-entity-error-EPUB2.zip