N.B. THIS IS NOT A VALD DESIGNATOR TERM!
The root describes a note that has no parent, i.e. at the highest level in outline view. If a root note has no siblings then it is also the cover note. Otherwise the first listed top level note is the cover note.
Action code can't use 'root' but the concept is relevant in the use of path references to notes.
In export codes, there is a ^root^ code.