Hotspots are hyperlinks. Clicking on a hotspot generally causes a different document to be displayed in one of the two Hyperview browser panes. For a summary of hotspot related behavior, see Summary of hotspot types, uses and behaviour, as well as the detailed information on how to use hotspots to trace signals throughout you system in the following articles: Going to a selected use of a value, Going to the source of a value, Clicking on hotspots in the content pane, Clicking on hotspots in the index pane, Double-clicking on hotspots.
Hotspot highlighting is covered in the following articles: Highlighting hotspots, Highlighting items in Hyperview, Highlighting the target topic with "Vegas Lights".
Function code hotspots can be enabled and disabled. See Enabling function code hotspots.