what am I missing?

I'm looking at adding links to track and share an entry to an Opal-based theme - for example, the way Smooth Sailing says "previous | memories | share | track | flag | next" on each entry. Given I can't find any reference to previous/next (for entries themselves, not DayPage or MonthPage), tracking or sharing in the default layer for Opal, what does Opal use to display these, or is it that it actually doesn't support them? It seems like this is usually based on the Core function print_linkbar, but Opal doesn't reference this, and print_linkbar specifically doesn't do nav_next and nav_prev according to the Core. If I call print_linkbar, what exactly will show up? I'm not sure what it does contain by default, or how it's displayed. I can't just try it because I don't have a paid account; the layout is for someone else's account.

I'm also not sure I could lift the code wholesale from, say, the Smooth Sailing layer instead, because I don't know if it will actually compile when transplanted. Is there an s2 sandbox available anywhere? I know there was one back in the old, old days...probably approaching nine years ago. Ack.