Comment 4 for bug 1703251

Uh, no, they don't match. And the issue appears to be unrelated to the paging thing, because I raised the max_opds_items value so they can all fit in a single page. I'm checking via Firefox pointed to http://127.0.0.1:8080/opds/ , not Aldiko. (Firefox is the one browser that displays the OPDS server in a convenient way -- IE has no clickable links, Chrome shows raw XML and Edge refuses to load the page. But hand-copying the URL from Firefox yields the same results, so it doesn't seem to be a browser issue)

Anyway... I have 36 authors with surnames beginning in "B". The Calibre GUI shows me 36. If I load the "B" author listing in OPDS, I get 36 names (hand-counted), as expected. But the "By Authors" OPDS page says that there are only 31 items under "B", which is plainly wrong.

The actual XML block for the "B" group is as follows:
<entry>
    <title>B</title>
    <id>calibre:category-group:authors:B</id>
    <updated>2017-07-10T02:44:24+00:00</updated>
    <content type="text">31 items</content>
    <link href="/opds/categorygroup/617574686f7273/42?library_id=E-books_library" type="application/atom+xml;type=feed;profile=opds-catalog"/>
  </entry>

As I said, this does not seem to be directly related to the OPDS paging, since it was unaffected by raising the max_opds_items value. But, coincidentally, it appears to affect only author groups with more than 30 names. ALL such groups in my library are affected. It's not a big annoyance, and I wouldn't have even noticed it if I wasn't trying to figure out the page limit thing, but it's there.