Last Update: 3/17/2016
Prior to Origin 9.1, adding drop lines to a 2D line plot required the following work-around:
Note: These methods of removing plot symbols tend to work better than setting Symbol Size to 0. Also, you may want to read this FAQ on dashed lines in Line + Symbol plots.
Starting with Origin 9.1, you can add drop lines directly to a line plot using controls on the Drop Lines tab of Plot Details.
Keywords:drop lines, line + symbol, symbol, symbol size