I've plotted several line charts in Excel using code from VB6.0. I have two questions about changes that I'd like to make to them. Firstly, all of my vertical axes start from zero, which is not the most sensible option most of the time. How can I make the lowest value of the y axis be just below the lowest value being plotted? The second question is how can I draw a line across the graph (in say, red) at a particular value of y, so that it is very clear to a viewer whether the current measurement is above or below the necessary limits.