sdd:flowCopy as claim

sdd:flow is the layout axis of a container — a sdd:Node root or a sdd:Section — one of down or right, defaulting to down when unstated (design spec §1).Copy as claim

The flex model guarantees document order along the flow axis is visual order: sections are placed in sdd:order with no reordering pass, so the order a section is declared in is the order it renders in along its container's sdd:flow axis.Copy as claim