In my case I've got to create articles where each article has a custom, unchanging "header" part far too rich for the title and the excerpt (it's to contain image, media etc), and then a few different pages of content. I've decided to do this using
<!--nextpage--> to keep it lightweight and easy for whoever will create the pages - treat the first page as the unchanging header and attach page 2, 3, 4 under a fixed set of links - an custom menu generated in that category, replacing standard pagination "Page 1 2 3 4" links.
In order to do that, I'll have to call
the_content() twice; once for page 1, and once for whichever page is chosen through the dedicated menu. Except I have no clue how to make
the_content() extract n-th page, other than through appending /n/ to the URL.
Is there some variable, function, plugin, modification to the code that lets me extract a specific page of paginated post?