sdd:fromAnchor
sdd:fromAnchor is the border and offset where an sdd:Edge leaves the boundary of its sdd:from instance — an sdd:anchor literal such as "right 50%"^^sdd:anchor.
An edge owns its connection (examples decision 9): each end is an anchor relative to its node's boundary, not a fixed pixel point. When a route pins interior waypoints, the renderer always closes the path from sdd:fromAnchor through those waypoints to sdd:toAnchor, so a connection holds by construction when either node moves — a stale waypoint can make an edge ugly, never disconnected.