Jon Peltier has instructions for adding a horizontal line to a chart:

http://www.peltiertech.com/Excel/Cha...s.html#AddLine


Eric wrote:
I would like to add threshold lines (horizontal lines) in a chart to show
maximum and minimum values. In algebra the equations would be for instance
y=100 for the max and y=55 for the minimum.
How can I do this without having to repeat the same values indefinitely in
the table or in the "=series" statement of the graph (repeated values being
in my example 100 for the max and 55 for the min.).


--
Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html