In the opening window, there are hundreds of them, of course. But, except of renaming chance, I totally confuse, what can I do with them. There are all enmasse: authors, series, tags... and what? For example, selecting anything in left panel, then clicking on arrow in center, does nothing. On the top, "Name of the category", with arrow, has no any value...
And Calibre's Guide is very pure, wrong organized. And most of the plugins has absolutly no help materials.
