[BobC]

Originally Posted by NiLuJe

@Winkelschraube: It'll only display inside an actual ePub 3 document that features a reference pagemap.

I came across the same issue with a book recently downloaded from Gutenberg. However the book was EPUB2 but had a pageList section in the toc.ncx :

<pageList id="pages" class="pagelist">
    <navLabel>
      <text>Pages</text>
    </navLabel>
    <pageTarget id="pt-1" value="1" type="normal" playOrder="4">
      <navLabel>
        <text>[Pg 5]</text>
      </navLabel>
      <content src="RFT_split2.html#Page_5"/>
    </pageTarget>
    <pageTarget id="pt-2" value="2" type="normal" playOrder="6">
      <navLabel>
        <text>[Pg 6]</text>
      </navLabel>

(much truncated)

So not just restricted to EPUB3. I hadn't seen this previously in Gutenberg books and it may be a modern innovation with their conversion process.

BobC