Identification of audio-only books in EPUB techniques

[jonaslil]

In 4.4.3 Instructions, step 2 checks for the presence of accessModeSufficient value "auditory". If present, it displays "Audio only" (compact explanation).

However, accessModeSufficient "auditory" can also appear in books with synchronized text and audio. In such cases, accessModeSufficient "textual" should also be included. See EPUB Accessibility Techniques 1.1, 3.3.

So accessModeSufficient "auditory" alone does not confirm a book is audio-only. To determine this, it seems necessary to also check for the absence of accessMode "textual", accessModeSufficient "textual", or other indications of text content.

The ONIX logic addresses this with the condition AND NOT synchronised_pre_recorded_audio, ensuring synchronized text and audio books are not misclassified.