The haystack module supports a smart site relation (hs:siteRef) that is valid for ControlPoints. If a ControlPoint has an hs:equipRef relation (direct or implied) to a component with the hs:equip tag and that equip component has an hs:siteRef relation to a component with the hs:site tag, an hs:siteRef relation is implied from the ControlPoint to that site component.