1. 11
  1. 1

    Not all of these have direct analogues with HTML5 (in fact, action buttons could even run shell scripts!) and some of their core conceits are rather different. Indeed, its most pervasive and interesting navigational mechanism is the concept of replacement: embedding the content referred to by a link (“replace button”) directly where it was referenced. This provided spatial context within a single master document.

    In Xanadu this is called stretchtext, & while it’s rare to see today, Computer Lib/Dream Machines lists it as one of the primary link types any hypertext system ought to implement (and the second easiest to implement, after jump links). HTML does in fact have something like this – the details tag – though in HTML this isn’t considered a link but instead part of the same document (a distinction that doesn’t make any sense in Xanadu, where all documents are assembled from transclusions by the front-end, but one that is vital to any system built on individual markup files that cannot reference each other except as entire chunks.)

    Brown University filmed a demo of one of their later (mac-based) hypertext systems – a descendent of HES – that supported stretchtext; I would be surprised if HES itself did not support it, simply because by the mid-80s most new hypertext systems were doing jump links only.