This property replaces data in the configuration file with data collected through a post into this web part. To specify more than one parameter, separate each with a semicolon (;). This will look for the parameter name in the connection file surrounded by % symbols.
Example: In the web part: customerID;contactID
In the URL: http://www.company.com/default.aspx?customerID=1&contactID=1
Inside the configuration file: %customerID% %contactID%