FUNCTION IfcAlignmentRepresentation
(Alignment : IfcAlignment) : IfcBoolean;

LOCAL
AlignmentRepresentations : SET OF IfcShapeRepresentation;
TwoDRep : SET OF IfcShapeRepresentation;
ThreeDRep : SET OF IfcShapeRepresentation;
CurveTwoD : SET OF IfcCompositeCurve;
CurveThreeD : SET OF IfcGradientCurve;
END_LOCAL;

(* no representation is okay *)
IF NOT EXISTS(Alignment.Representation) THEN
RETURN(TRUE);
END_IF;

(* Alignment.Representation exists so assign *)
AlignmentRepresentations := Alignment.Representation.Representations;

(* one representation is either Curve2D or 3D *)
IF SIZEOF(AlignmentRepresentations) = 1 THEN
IF SIZEOF(AlignmentRepresentations[1].Items) <> 1 THEN
RETURN (FALSE);
END_IF;
IF SIZEOF(QUERY(twoDee <* AlignmentRepresentations | twoDee.RepresentationType = 'Curve2D')) = 1 THEN
CASE TRUE OF
'IFCGEOMETRYRESOURCE.IfcCompositeCurve' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
'IFCGEOMETRYRESOURCE.IfcOffsetCurveByDistances' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
'IFCGEOMETRYRESOURCE.IfcPolyline' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
END_CASE;
END_IF;
IF SIZEOF(QUERY(threeDee <* AlignmentRepresentations | threeDee.RepresentationType = 'Curve3D')) = 1 THEN
CASE TRUE OF
'IFCGEOMETRYRESOURCE.IfcGradientCurve' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
'IFCGEOMETRYRESOURCE.IfcOffsetCurveByDistances' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
'IFCGEOMETRYRESOURCE.IfcSegmentedReferenceCurve' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
'IFCGEOMETRYRESOURCE.IfcPolyline' IN TYPEOF(AlignmentRepresentations[1].Items[1]):
RETURN(TRUE);
END_CASE;
END_IF;
END_IF;

(* 2 representations and 3D BaseCurve reference equals 2D representation *)
IF SIZEOF(AlignmentRepresentations) = 2 THEN

TwoDRep := QUERY(twoDee <* AlignmentRepresentations | twoDee.RepresentationType = 'Curve2D');
CurveTwoD := QUERY(item <* TwoDRep[1].Items | 'IFCGEOMETRYRESOURCE.IfcCompositeCurve' in TYPEOF(item));
ThreeDRep := QUERY(threeDee <* AlignmentRepresentations | threeDee.RepresentationType = 'Curve3D');
CurveThreeD := QUERY(item <* ThreeDRep[1].Items | 'IFCGEOMETRYRESOURCE.IfcGradientCurve' in TYPEOF(item));

RETURN((SIZEOF(CurveThreeD) = 1) AND (SIZEOF(CurveTwoD) = 1) AND (CurveThreeD[1].BaseCurve :=: CurveTwoD[1]));

END_IF;
(* Missing an IfcSegmentedReferenceCurve various placement option implementation. *)

RETURN(FALSE);

END_FUNCTION;