| IfcProject | P | IfcProject or another object from IFC database | Generic Data |
| Start | P | Start Point | Point |
| Direction | D | Start Direction | Vector |
| StartRadius | S | For a NONLINEAR horizontal segment type the radius of the curve at the start point, If the radius is 0 it shall be interpreted as INFINITE. Positive values imply a CCW direction whereas negative CW. | Number |
| EndRadius | E | For a NONLINEAR horizontal segment type the radius of the curve at the end point, If the radius is 0 it shall be interpreted as INFINITE. Positive values imply a CCW direction whereas negative CW. | Number |
| Length | L | SegmentLength | Number |
| Shape | S | Shape Predefined type of the horizontal alignmnent segment (0=LINE 1=CIRCULARARC 2=CLOTHOID 3=CUBIC 4=HELMERTCURVE 5=BLOSSCURVE 6=COSINECURVE 7=SINECURVE 8=VIENNESEBEND) | Integer |
| StartTag | T | Start Tag | Text |
| EndTag | T | End Tag | Text |