Using MultiSelect parameters in BSH functions

Hello,

I have a report that has several MultiSelectList parameters of data type String. I need to iterate through these lists to build a complex string object using data from each of the lists. I was thinking of using a BSH function to do this. My problem is that I don't know how to get these parameters into the BSH function, or what the objects would look like when they get there. Can you help me?

Thanks.