With this command you can convert an arbitrary two-dimensional polyline into a longitudinal alignment, without the need of having to define the horizontal elements of the alignment first. This allows designers of watercourses, railroads, etc. to use the possibilities of PLATEIA to their advantage too.
After starting the Convert PLINE to longitudinal alignment (21G2) command and selecting the appropriate polyline, the program creates a new longitudinal alignment along the selected polyline on the 20_AXISNAME_LONG_AXES layer.