"Serial ports tree" dynamically represents current serial port configuration in your system. It shows both shared and unshared serial ports, applications that are connected to serial ports, connection status, sent/received data counters and custom access rights (if any) set to applications for advanced serial port management. 
Once serial port is shared, its icon will be changed to and new groups ("Connected applications" and "Custom rights") will be added. "Connected applications" group lists all applications which are currently connected to shared serial port. Each entry is separated by application's name (full path to execution file) and contains the following parameters:
"Custom rights" group displays the list of applications that the custom rights were set for. Each entry in the list is separated by application's name (full path to execution file) and has only one parameter: serial port access rights string, written in the following format: Read/Write/Control", where "Read" means that application can read communication data from serial port, "Write" - application can write data to serial port and "Control" - application can manage serial port control lines (RTS, DTR, DCD, etc). If any of the options is omitted, dash ("-") is used. For instance: "Read/Write/-" means that application can read and write to serial port but can not manage control lines.
Important notice: if the same application (which has "Manage control lines" option enabled) connects to shared serial port, only the first application with this type of rights will be able to manage control lines.