The designator cover represents the top level note in the hierarchy, or the first listed if there is more than one at this level. It will be the first listed in an outline window that shows the whole document. It has an $OutlineOrder value of '1'. The cover note will be the first listed root note if there is more than one note at the highest Outline level.
Designators don't allow offset references as with attributes. Thus $Name("Some note") works but child("Some note") doesn't. If an offset designator is needed use find() instead.