joerg-krause writes
The -i option can be used to set the source by index, whereas the -I option can be used to set the source by name for the OpenHome product service of a UPnP renderer.
This is handy to enable/disable the Songcast Sender or any other external source, e.g. use scctl -I <device name > PL-to-Songcast to enable the Songcast Sender Service.