FOCUS Enhancements 3.2 - Manual (Page 158)

External Control Commands
144
Command Summary
Remember all commands are either upper case or lower case
characters as well as other ASCII characters. Some address
arguments are optional and will be designated by () whereas
mandatory addresses will be designated by <>.
The channel parameter is required for certain commands. These same
External Control Command parameters are also used in Visual Circuits
multi-channel products. The default channel for the Firefly-SC (single
channel player) should always be ‘0’.