The way to find out is to look at the sketch:
“MSG” is a count of message number, it increments by one for each message sent. This allows missing data to be identified (but never restored, unfortunately).
“Vrms” is the voltage in 1/100ths of a volt.
“P1” - “P4” are the real power value for the 4 c.t. inputs in watts.
“E1” - “E4” are the accumulated energies for the 4 c.t. inputs in watt-hours.
“T1” - “T3” are temperatures in 1/100ths of a degree Celsius.
“pulse” is an accumulating count of pulses as detected by the pulse input.
The accumulated values start from zero when the sketch starts or is reset. emonCMS is able to handle that reset in most circumstances.