Content Description Template on PS/nVision reports

I'm fairly new user of PS Finance, and I've recently started playing with PS/nVision reports. One of the fields in the nVision Web Output screen is called "Content Description Template". The tooltip reads: "Enter a description of the report instances for identification in Report Manager. Use variables to dynamically create the descriptions. Examples: Stmt. Rev & Exp, Vacation Register - %SFV%"

I'm trying to understand how to use this field...sometimes it seems to want %RTT%-%SFV%, other times just %RTT%, and still other times it just wants to be blank. Besides trial and error, can anyone offer a translation of what the heck this field is doing?