Emission modes

The emission mode of a transmission is described by a series of numbers and letters representing the following components:
  1. The modulation of the main carrier of the transmission
  2. The nature of the signal or signals modulating the main carrier of the transmission
  3. The kind of information to be transmitted using the station
The symbols used to describe each component of the emission mode are:

 
Component Description Symbol
Modulation of the main carrier Main carrier:
(a) is amplitude modulated; and
(b) uses double-sideband		 A
  Main carrier:
(a) is amplitude modulated; and
(b) uses single-sideband, full carrier		 H
  Main carrier:
(a) is amplitude modulated; and
(b) uses a single-sideband, reduced or variable-level carrier		 R
  Main carrier:
(a) is amplitude modulated; and
(b) uses a single-sideband, suppressed carrier		 J
  Main carrier:
(a) is amplitude modulated; and
(b) uses independent sideband		 B
  Main carrier:
(a) is amplitude modulated; and
(b) uses vestigial sideband		 C
  Main carrier:
(a) is angle modulated; and
(b) uses frequency modulation		 F
  Main carrier:
(a) is angle modulated; and
(b) uses phase modulation		 G
Signals or signals modulating the main carrier Signal modulating the main carrier is a single channel containing quantized or digital information without the use of a modulating subcarrier 1
  Signal modulating the main carrier is a single channel containing quantized or digital information with the use of a modulating subcarrier 2
  Signal modulating the main carrier is a single channel containing analog information 3
  Signal modulating the main carrier is 2 or more channels containing analog information 8
Kind of information to be transmitted Telegraphy for aural reception A
  Telegraphy for automatic reception B
  Facsimile transmission C
  Data transmission, telemetry or telecommand D
  Telephony E
  Television (video) F
  A combination of any of the kinds of information described in the previous items W

Examples:

Mode Description Emission Code
AM amplitude modulation, double sideband, full carrier, voice A3E
FM frequency modulation, voice F3E
PM phase modulation, voice G3E
SSB amplitude modulation, single side band, suppressed carrier, voice J3E
SSB-TV amplitude modulation, single side band, suppressed carrier, image J3F
TV Television using FM F3F
RTTY telegraphy using FSK, no modulating audio tone F1B
RTTY telegraphy using AFSK, modulating audio tone F2B
packet FM data F1D
CW amplitude modulation, double sideband, full carrier, data A1A
silence unmodulated carrier N0N

 
Sources:
The American Radio Relay League
The Australian Communications Authority
Gordon West license study guides