I'm looking at the documentation for IBM's Rational Software Architect.
The documentation opens in some kind of special help viewer; the left pane has a hierarchical list of help topics where you can open and close individual nodes; the right side shows the content.
The content often, but apparently not always, ends with a link to the parent topic and/or to the next and/or previous topics at the same hiearchy level. However, in order to read all the topics in a given hierarchy, including sub-hierarchies (say, you're at 2.5 and you want to read 2.5.1, 2.5.2, 2.5.3, 184.108.40.206, 220.127.116.11, 2.5.4, 2.5.5, 18.104.22.168, 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11, 2.5.7, and 18.104.22.168, in that order), you have to remember where you are and keep clicking various points in the screen with your mouse, and choose whether to select topics from links within the current topic or from the hierarchy at the left -- and the links within the topic often don't have exactly the same name as the topic name listed at the left, so you're not always sure whether two links are the same!
In the command-line texinfo viewer(s?) I'm familiar with, I could simply keep pressing space: IIRC, its default action is something like
- page down, if there's more text in the current topic
- select the first menu item on the current page if there are no further pages
- select the first sibling of the current topic ('next') if there are no menu items on the current page
- select the first sibling of the current topic's parent ('up-and-next') if the current topic has no (more) siblings.
- (and if the current topic's parent has no (more) siblings, I think it would try up-up-next, up-up-up-next, etc., until it got to the top level and found that the current topic's topmost ancestor has no more siblings, at which point it would give you an error message and tell you so.)
which is pretty much what I'd want in such a case.
But a lot of software these days seems to be optimised for mouse use rather than ease-of-use via keyboard, OSISTM.