remove linear=no from <itemref idref="cover" linear="no" />

[ousia]

As already discussed in #1593, linear=no makes the <itemref> auxiliary. Breaking the linearity of an <itemref> allows the reading system to present its content in a different order from that one specified in the <spine>.

From the ePub 2 spec:

Specifying whether an OPS Content Document is primary or auxiliary is useful for Reading Systems which opt to present auxiliary content differently than primary content. For example, a Reading System might opt to render auxiliary content in a popup window apart from the main window which presents the primary content. (For an example of the types of content that may be considered auxiliary, refer to the example below and the subsequent discussion.)

Reading Systems are not required to differentiate between primary and auxiliary content, and for the requirements and recommendations given in this section may consider all OPS Content Documents in spine to be primary, regardless of the value of the linear attribute.

Or the ePub 3 spec:

The itemref element linear attribute indicates whether referenced item is considered primary (yes) or auxiliary (no) in the spine. This attribute may be used to enable Reading Systems to distinguish presentation of body content from supplementary content which might be, for example, presented in a popup window or omitted from an aural rendition.

From both descriptions, I think it is important to remove linear=no from <itemref idref="cover" linear="no" /> in both ePub 2 & 3 formats.

As far as I understand, the book cover is no axiliary content. Either way, it shouldn’t be presented in a popup window.

Many thanks for your help.

[elmimmo]

Another argument in favor of the proposed fix is that, if an ereader system is expected to hide non-linear content from its linear flow, it should also be expected that all that non-linear content will therefore be accessible from a hyperlink in the body of the linear content, else, the person reading the book would never be able to access it.

Why would one ever add a hyperlink to the cover image in the body of the book?

[mpickering]

Seems sensible.