This amounted to choosing some triplet of letters, say 'WHJ'.
也就是要设定一个三位的字母串，比如WHJ。
The most naive indicator system would have been simply to transmit 'WHJ', and follow it with the enciphered message.
最原始的指示信号机制，会直接发送WHJ，然后接下来发送密文。
However, it was made more complicated than that.
在实际中，会弄得更复杂一些，
The 'WHJ' was itself enciphered on the machine.
WHJ本身也会在机器里进行编码。
For this purpose a so-called ground-setting was also laid down in the instructions for the day.
为了实现这个目的，每天的操作指南中，还会包括一个当天的所谓底层设定。
This, like the rotor order, plugboard and ring-setting would be common to every operator in the network.
这些与盘位、带位和配线板一样，是每个操作员都非常熟悉的。
Suppose the ground-setting were 'RTY'.
假如底层设定是RTY。
Then the cipher clerk would set up his Enigma with the specified rotor order, plugboard and ring-setting
操作员首先要给他的谜机设定盘位、带位和配线板，他会转动转盘，
He would turn the rotors to read 'RTY'.
设定初始盘位为RTY，
Then his job was to encipher, twice over, his own choice of rotor setting.
然后对他自行选定的盘位进行编码。这个盘位指示要重复两次，
That is, he would encipher 'WHJ WHJ', producing say 'ERIONM'.
也就是说，他要对WHJWHJ进行编码。假如说编码的结果是ERIONM，
He would transmit 'ERIONM', then turn the rotors to 'WHJ', encipher the message, and transmit it.
那他就将ERIONM发送出去，然后再把初始盘位设定为WHJ，开始编码正式的信息并发送出去。