Have you ever drawn a line from a point node and become frustrated because the Z value of the line absorbs the elevation value of the point? Next thing you find that you have a drawing with a bunch of lines all drawn at different elevations. Yes, there are times you want this, but there are also times you don't.
If you decide that you need to draw several lines from several point nodes and you want to guarantee the lines will be drawn at a 0.00 elevation then set your OSNAPZ system variable to 1. The OSNAPZ controls whether object snaps are automatically projected onto a plane parallel to the XY plane of the current UCS at the current elevation.
0 - Osnap uses the Z-value of the specified point
1 - Osnap substitutes the Z-value for the specified point with an elevation set for the current
If you choose to have your elevation something other than 0.00 then type in ELEV in at the commandline and set the desired value.
WARNING: The OSNAPZ is a system variable and therefore, when you change this you are changing this setting for any and all drawings in which you will be working.