When I asked readers to suggest some small Revit API apps, Nathan suggested:
Something that will highlight any keynotes that have lost their host and show up as blank. Actually a tool that highlights User Keynotes versus the other types would be cool, too. We don’t like User Keynotes in my office, but many people still insist on using them for some reason. Being able to pick out how many there are in a given view would be useful.
You can use the semicolon-delimited list of element IDs along with Revit’s “Select By ID” tool to select groups of tags based on their type or orphan-status.