OptionalGlobalOptionalguidStation at distance 0, metres — written to the start referent's Pset_Stationing.
OptionalStationStation equations (§14), in order along the alignment; each becomes an IfcReferent.
OptionalVerticalThe vertical layout (mapping spec §12). When present the alignment also
gets an IfcAlignmentVertical and an IfcGradientCurve 'Axis'
representation, and the composite curve moves to 'FootPrint'.
Deterministic GlobalId seed for this alignment's owned entities.