The designator children describes any direct child of the current note.
This designator removes the contextual ambiguity of older usage of 'child' for both group and item scope usage. By comparison the 'child' designator is always assumed to apply to item scope (i.e. one referenced ontainer only).
As designators ignore map adornments, a container note with just adornments on it but child notes with evaluate as having a $ChildCount (the number of adornments) but no 'children' (the number of notes).