A construction xline can be placed anywhere in 3D space and extends to infinity in both directions. To create an xline, use the AddXLine method. This method specifies the line by the two-point method; you enter or select two points to define the orientation. The first point, the root, is considered the midpoint of the construction line.
The following example code creates an XLine object using the two points (5, 0, 0) and (1, 1, 0).
Dim xlineObj As AcadXline
Dim basePoint(0 To 2) As Double
Dim directionVec(0 To 2) As Double
' Define the xline
basePoint(0) = 2#: basePoint(1) = 2#: basePoint(2) = 0#
directionVec(0) = 1#: directionVec(1) = 1#: directionVec(2) = 0#
' Create the xline in model space
Set xlineObj = ThisDrawing.ModelSpace.AddXLine _