Type
Select the type of reference dimension to place. For an absolute reference dimension, you must specify the exact coordinates of the referenced object. For a relative reference dimension, the software calculates the exact coordinates using the values you define which are offset from the reference point.
Reference point
Type the units to set for each direction. To specify a West, South, or Down coordinate, use a negative value. For example, to specify 1000mm West, type -1000 in the East/west box. For an absolute reference dimension, you can use the Global Offset list to determine how the software interprets the coordinates you enter. If you select Global Offset, the software determines the actual coordinates of the reference dimension by adding the global offset defined for the pipeline to the Coordinate values you enter. If you select Absolute, the Coordinate values you enter are the actual values of the reference dimension.