Fouled board
A board where one or more cards were returned to the wrong slot.
Or, in a game with multiple sections, a board of the same number differed in vulnerability or dealer between sections.
ACBLSCORE handles FOULED board, the Director does not need to know the mathematical equation.

Skipped / Not Played
Same term for a board scheduled to play, but not played.
If there is any chance the board will be played later, the Director can use L (late) rather than N (not played)
A board "not played" is the mathematical equivalent of giving the pair their session average. (this seems to be a contentious point)
So if you were scheduled to play this against the weakest pair in the game, and may get a top, you lose.
If you were scheduled to play this against the strongest pair, you win.
Not played should be used in extreme cases, ie civil and medical emergency and not for slow play, late pair.
For all other reasons, the Director should adjust the board awarding an Artificial Adjusted Score.