Topics That Leave No Instance

So we wanted to delete a topic, but no instance of that topic is left in the hierarchy. What next?

Then all traces of that topic will be removed from the index too, including terms that are based on it. But where does this topic go after it is deleted? There are two possibilities:
• Topic is added to 'Available Topics' (default), or
• Topic is excluded.
Whether one or the other of the above takes place, it depends on the setting in Options > Application Options > When deleting topics that leave no instance. If you didn't change this option, such a topic is always added to 'Available Topics'. If you opted for excluding such topics, they'll be listed as valid in 'Excluded Items', from where you can restore them anytime (see Exclusions).