What's the string for a single parameter

When i want to buld a url string in Xcelsius to open a webi report or another flash file, what is the single parameter tag?

I am using "&IsSPARAMETERNAME=" for a report that has 3 multiple parameters. Can I use the same "&IsS" with the upper S when i want to write a one-parameter string that uses only 1 parameter and not more than 1?