1NT - 2D - 2H - 4D - ?
Opponent ask the meaning of 4D and opener said he did not know. After the auction the responder said they had an agreement that 4D was a splinter. Opponent then called the director and stated she would have doubled for a diamond lead if she knew it was a singleton and thus wanted an adjustment.
Later, the opponent pointed to law:
21.3. When it is too late to change a call and the Director judges that the offending side gained an advantage from the irregularity he awards an adjusted score.
So if a player states he has forgotten the meaning of a conventional call, then does this constitutes an irregularity such that the director can adjust the score?
Plus... it's free!