Once you’ve developed a taxonomy, of course you want to use it. And before using it, you want (or should want) to test it. And, of course, the use is two ways. You can apply it to the records, for indexing, and you can use it for search, too; both of those applications are use tests at first, and can serve as use tests again for maintenance of the taxonomy. Once you get into the maintenance phase, you have to be able to edit and otherwise change lots of parts of the terms. You might change the status of the term itself, what it is called; for example, you could change the primary term that you use and put some other word in as the non-preferred term. You might want to delete or add a relationship. Of course, you want to add new terms. You might want to move the branches around. All of these things are part of routine taxonomy maintenance.