Lines are used for map borders, or where you require a straight edge with 3 nodes or less. This is the line command you get when you use the default Line 
:
The prompt reads "1st point:". Select a starting point for the line by using the crosshairs and left-clicking or by typing numeric coordinates.
Now the prompt reads "Next point:" and the cursor becomes a rubber-band (stretching) line anchored at the first point you selected. Use the cursor or type coordinates to select an ending point for the line. CC3 draws a line entity to replace the cursor, then stays in the LINE command so you can draw a series of connected lines. Right-click to stop drawing lines.
Text equivalent: LINE