more than one marker in charts

Hi,

I found Tricks with Charts article that explains how to add horizontal lines to charts. Very handy if you want to have a quick look at thresholds. But I would be even more happy if there was a way to add more than one line. I tried to add more values to the custom property using various seperators, but it only accepts one value :-(

Any ideas how to achieve this?

Thanks

Henning