extend-string ("ext")

See this command in the command table.

To access this command:

Edit ribbon >>Edit >> Extend.
Home ribbon >>Edit >> Extend >> Add Segment to String.
Edit ribbon >>Edit >> Extend >> Add Segment to String.
Using the command line, enter "extend-string"
Use the quick key combination "ext".
Display the Find Command screen, locate extend-string and click Run.

Command Overview

Extends a string by adding new points to its end point. Additional string points are added interactively or using the command line coordinate entry system. You can also perform a combination of interactive and command line entries, which could be useful to maintain a required gradient or target 3D location.

Left-click to place a point without snapping, and right-click to snap to data.
Data selection and snapping honours the current data selection and snap settings.
The string is only extended from the last point - the end of the string.
To extend the string from the other end, use reverse-string (to reverse the string point order) before running this command.

Command steps:

Run the command.
Select the string to be extended.
Digitize additional points or add command line coordinates.