Set command sequence undoability to kUndoNotRequired?

I was trying to prevent a command sequence from showing up in the command history by setting its undoability to kUndoNotRequired. And at run time,
I get the following assertion:

CommandSequence::SetUndoability(): unsopported undoability

Here is the gist of the code.

ICommandSequence* sequ = CmdUtils::BeginCommandSequence();
sequ->SetUndoability(ICommand::kUndoNotRequired);
// set sequ name
// run the commands
CmdUtils::EndCommandSequence(sequ);

So this is an undocumented "feature" of the API?

Nick