This is a selection from the NetRadio Server (NrServer) command set:

MODE_RECEIVER
    This puts your connection into receiver mode.

MODE_TRANSMITTER Freq Label
    This puts your connection into transmitter mode. Freq is a number between
    880 and 1080 meaning 88.0 MHz en 108.0 MHz, which are Dutch FM Radio lower
    and upper frequencies. The Label could be anything like Radio 3. This 
    label is sent to the receiver when it tunes in on the transmitter's 
    frequency. Example:

        MODE_TRANSMITTER 918 Radio 3

LIST_RECEIVER
    This lists all Receivers currently connected to the server.

LIST_TRANSMITTER
    This lists all Transmitters currently connected to the server.

TO_ALL
    This passes a message to all connections to the server, example:

        TO_ALL Hi All!

    Well, see for yourself!

TO_RECEIVER
    This is like TO_ALL, limited to all receiver connections. It can be used
    for RDS like applications.

TO_TRANSMITTER
    This is another variation limited to all transmitter connections.

TO_TUNED
    This variation is for transmitters only. It passes a message to all
    tuned receivers.

The next commands are receiver commands:

TUNE
    This makes the receiver tune in on a specified frequence, example:

        TUNE 918

    The Server replies wether or not you receive a signal.

TUNE_UP
    This makes the receiver tune up from a specified frequence, example:

        TUNE_UP 918

    The Server tunes up in steps of 1 (0.1 MHz) Showing for each frequency
    if there's a signal. It stops searching when a frequency with a signal
    is found.

TUNE_DOWN
    This makes the receiver tune down from a specified frequence, like TUNE_UP.

MUTE_ON
    This makes the receiver stop passing audio data, which is the default. This
    reduces the network-load. If there are no receivers listening on a 
    frequency the responsible transmitter is passed the MUTE_ON command too.

MUTE_OFF
    This is the opposite of MUTE_ON.

QUIT
    This makes the server terminate the connection.

The next is a transmitter command:

PING
    It is the reply to a PING from the server. The server sends a ping every
    5 seconds. If a transmitter hasn't sent a ping for 30 seconds, it's
    disconnected.
