Graft branches (rarely needed): set a vessel's type to Outer or Inner and fill in the branch; it sets the fen.
Enter which way it points (↓ down or ↑ up), its diameter, its (stent) length, and the gap from its outlet to the ostium.
The fen: an outer branch's fen is the gap plus the length above the ostium (e.g. a 2 to 2.5 cm branch leaving about 1 cm to cannulate puts the fen 3.5 to 4 cm above the ostium). An inner branch's outlet is its fen, at the ostium unless you type a gap. A blank fen size is the branch's diameter + 1.
On screen and on paper: the fen moves there, and arcs, strut checks and Best fit follow it. The maps draw the tube (outer solid, inner dashed, its open end heavier) and a dotted circle at the ostium. On the plan sheet and the build sheet the Absolute and Adjusted lines give the ostium, and a Branch fen line below them gives the fen.
Alpha taper: the tube leans toward the zero line on the map, as the struts do: the graft is narrower lower down, so the same clock position is fewer mm from the zero line. On the graft the fen is directly above the ostium, at the vessel's clock.
Checks: room for an outer branch (AVD − IVD at least its diameter, or a diameter-reducing tie or an inner branch); an outlet gap under 5 mm (amber: little room to cannulate); a tube over another fen; a tube off the fabric; on the Treo, an inner branch within 10 mm of the flow divider.