Understanding main.h (Execute)

//Valid communication from USB?
			if(cmd_ready_usb != 0)
			{
				cmd_ready_usb = 0;
				//Cheap trick to get first line	//ToDo: support more than 1
				for(i = 0; i < PAYLOAD_BUF_LEN; i++)
				{
					tmp_rx_command_usb[i] = rx_command_usb[0][i];
				}
				//payload_parse_str() calls the functions (if valid)
				result = payload_parse_str(tmp_rx_command_usb);
				//LED:
				if(result == PARSE_SUCCESSFUL)
				{
					//Green LED only if the ID matched and the command was known
					new_cmd_led = 1;
				}
			}