is a variable defined in `
Its value is
(command-history-mode list-command-history electric-command-history)
A list of symbols to be ignored by `default-command-history-filter'.
If that function is given a list whose car is an element of this list,
then it will return non-nil (indicating the list should be discarded from
Initially, all commands related to the command history are discarded.
You can customize this variable.