After seeing the annoucement, Announcement: Keyboard shortcuts are now integrated into the site, I just had to enable keyboard shortcuts. I ran into the following problem, which is not one of those mentioned in New keyboard shortcut integration problems?
On pages displaying lists of questions, the O shortcut is described as "order questions by", but it actually appears to be a way to switch between the different tabs on that page. Usually those are synonymous, but not so when browsing questions by tag. E.g., when browsing questions tagged with Jena, the leftmost tab is "info", which is not a question ordering:
That said, pressing O, then I, does bring us to the info tab, but once we're there, we can't be back to the other tabs. O isn't enabled on the tag info page (there's nothing to order, I suppose), but there aren't any shortcuts to get to the other tabs, either: