sdd:fromStencil
sdd:fromStencil names the marker drawn at the from end of an sdd:Edge — for example an arrowhead or a diamond — resolved through the same theme system as sdd:shape and sdd:style.
Stencils are per-end, not per-edge: sdd:fromStencil and sdd:toStencil are independent, so an edge can carry a marker at one end only, or different markers at each. They are also template-mappable (examples decision 9) — a diagram template can bind a fact predicate like partOf to a specific stencil (a diamond, in the common containment convention) without the author choosing it by hand.