Allows to define new tags: simply type the name of the new tag and, with the caret on it, press Ctrl+T keys.
Allows to replace/edit a tag: simply move the caret on the tag name in the code text and press Ctrl+T keys to open the Tag list dialog (by closing the Tag list dialog pressing Ok o the Enter key the selected tag will be entered/replaced in the current selection).
Provides code completion (type the beginning of the name of something and press Ctrl+Space) for: