What is directly inside each sheet of a project, by sheet NAME - so one entry however many times a sheet is instantiated, with the sheets inside it NAMED rather than held. That costs one pass over each canvas and not the design's expansion, and it makes a sheet that contains itself representable without anything lazy. It deliberately holds nothing that depends on where a sheet sits: label path, access path, breadcrumb name, size and depth are all properties of an OCCURRENCE, and a design several routes reach one sheet by has many occurrences of one entry here. Those are filled in by materialiseTree, for the occurrences that are going to be looked at.