RJ> Things like 16K0F3W must mean something to someone - presumably the
 RJ> ITU!

OK, Here goes.  The first four digits specify the bandwidth of thetransmission.  16K0 is engineering notation for 16.0 kHz, indicating a 16 kHz wide transmission.  The letters H (Hz), K (kHz), M (MHz) and G (GHz) are used to represent the position of the decimal point.

Examples are:

H005 = 0.005 Hz
H100 = 0.1 Hz
15H5 = 15.5 Hz
2K40 = 2.4 kHz

The next letter specifies the type of modulation:

N - Unmodulated carrier
A - AM, Double sideband
H - AM, Single sideband, full carrier
R - AM, Single sideband, reduced or variable carrier
J - AM, Single sideband, suppressed carrier
B - AM, Independent sidebands
C - AM, Vestigial sidebands
F - FM
G - Phase modulation
D - Emission in which the main carrier is amplitude modulated as well as
    frequency or phase modulated either simultaneously or in a
    pre-established sequence.
P - Unmodulated pulses
K - Pulses modulated in amplitude
L - Pulses modulated in width/duration
M - Pulses modulated in position/phase
Q - Pulses in which the carrier is frequency or phase modulated during
the
    period of the pulse.
V - Pulses that are a combination of P, K, L, M or Q or is produced by
    other means.
W - Cases not covered above, in which an emission consists of the main
    carrier modulated, either simultaneously or in a pre-established
    sequence, in a combination of two or more or amplitude, frequency,
    phase or pulse modulation.
X - Cases not otherwise covered.

The sixth symbol specifies the nature of the signals modulating the
main carrier:

0 - No modulating signal
1 - Single channel containing quantized or digital information without
    the use of a modulating sub-carrier.
2 - Single channel containing quantized or digital information with the
    use of a modulating sub-carrier.
3 - Single channel containing analogue information
7 - Two or more channels containing quantized or digital information
8 - Two or more channels containing analogue information
9 - Composite system with one or more digital/quantized channels and
    one or more analogue channels.
X - Cases not otherwise covered.


The seventh symbol indicates the type of information to be transmitted:

N - No information transmitted
A - Telegraphy for aural reception
B - Telegraphy for automatic reception
C - Facsimile
D - Data transmission, telemetry, telecommand
E - Telephony (including sound broadcasting)
F - Television (video)
W - Combination of the above
X - Cases not otherwise covered


The eighth letter (if present) specifies additional information about
the
signal:

A - Two-condition code with elements of differing numbers and/or
    durations.
B - Two-condition code with elements of the same number and duration
    without error correction.
C - Two-condition code with elements of the same number and duration
    with error correction.
D - Four-condition code in which each condition represents a signal
    element of one or more bits.
E - Multi-condition code in which each condition represents a signal
    element of one or more bits.
F - Multi-condition code in which each condition or combination of
    conditions represents a character.
G - Sound of broadcasting quality (monophonic).
H - Sound of broadcasting quality (stereo or quadraphonic).
J - Sound of commercial quality (other than category K or L).
K - Sound of commercial quality with the use of frequency inversion
    or band-splitting.
L - Sound of commercial quality with separate frequency-modulated
    signals to control the level of demodulated signal.
M - Monochrome
N - Colour
W - Combination of the above
X - Cases not otherwise covered.

Finally (whew), a ninth symbol may be present that indicates the nature
of multiplexing employed:

N - None
C - Code-division multiplex
F - Frequency-division multiplex
T - Time-division multiplex
W - Combination of frequency-division and time-division multiplex
X - Other types of multiplexing

So that is it.  Hope this has been of some help.

Regards,

Rick.