It is interesting that Sigil and Calibre convert series and position in slightly different ways in epub3 made from epub2. I assume both are "correct" if that is how to put it. And direct entry results in a third version of the data:
Original epub2:
Code:
<meta name="calibre:series" content="Robert Macdonald"/>
<meta name="calibre:series_index" content="16.0"/>
After Calibre conversion to epub3:
Code:
<meta property="belongs-to-collection" id="id-4">Robert Macdonald</meta>
<meta refines="#id-4" property="collection-type">series</meta>
<meta refines="#id-4" property="group-position">16.0</meta>
After Sigil epub3-itier plugin:
Code:
<meta id="series" property="belongs-to-collection">Robert Macdonald</meta>
<meta refines="#series" property="collection-type">series</meta>
<meta refines="#series" property="group-position">16</meta>
And if I enter the data directly into a new epub3 book in Sigil this is what appears in the opf:
Code:
<meta property="belongs-to-collection" id="num">Robert Mcdonald</meta>
<meta refines="#num" property="group-position">16</meta>
<meta refines="#num" property="collection-type">series</meta>
No wonder epub3 is a bit tough to get the old head around.