Raftered roofs are coupled or non-coupled; splices in rafters and ceiling joists occur only at supports, using fishplates both sides (length at least six times the depth, at least 19 mm thick) or laps of at least three times the depth, fixed with the nails or bolt the clause sets. Coupled roofs have a pitch of at least 10 degrees and each opposing rafter pair is fixed to a ceiling joist and a collar tie; where such a roof has no struts and only nominal fixings, external walls may be no more than 6000 mm apart under sheet roofing and 4000 mm apart under tiles unless designed. Non-coupled roofs have rafters on walls, ridge and intermediate beams; trusses are designed to engineering principles and AS 1720.1 with consistent wind criteria.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.