Constructional lines are complex structures that can be used like a line. Typical example is wall structure in an architectural floor plan.
The principle of constructional line is, that repeated pattern is saved as a constructional line type. You can then drawn lines using this constructional line type.
The name Constructional line is somewhat misleading, because it is actually a symbol matrix, not a line type. Program provides commands, with which you can automatically draw, define and edit these symbol matrices. For example, Draw a constructional line function will calculate the correct scale and number of symbols needed to draw a line of certain length.
You can select constructional line functions from the Constructional line toolbar.