whether the user opens and closes this node. Not the same as NodeMultiRoute: a sheet with nothing inside it has nothing to reveal, so it gets no toggle, and a leaf reached two ways is exactly that case - which is why placement cannot be read off this

the instance on show. This is a SimSheetName, which is what Wave.SheetId holds, so it is what selects the waves to list. None where the simulation has no instance here - a sheet with nothing on it, or a simulation of an earlier version of the design

the sheet instances of this node's sheet that lie inside the instance chosen at its parent, alphabetically - so the head is what a node with nothing recorded about it shows

design-time sheet names from the top sheet down to this node - the node's identity, and the key under which the model remembers what is open and which instance was chosen

whether more than one route from the top sheet reaches this node's sheet, so that it appears in the hierarchy more than once. Such a sheet has no place in the flat top level of the signal list - which of the routes would a single row stand for? - so its row is drawn inside each parent that instantiates it instead