/\?(C=N;O=D|C=M;O=A)?$/;
                     ^

[download]

WHy do you need that last question mark? That way it will also match \?$. Probably not what you want.

It would also help if your error description was better than "DOESN'T WORK AS EXPECTED"

In reply to Re: Difficult? regex by moritz
in thread Difficult? regex by Anonymous Monk

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