To clarify about error notes
BCS will certify varieties on paper money, such as a missing leaf (2002 $5.00) or paper printing error (2005 $10 BTU and BTT), but cutting errors, ink errors, or number errors will not certified as such. For cutting error of folding errors, the degree and serverity of the error is put into question, making certifying it a rather touchy subject. Serial number errors change the description of the note, making it hard to officially classify (which of the two serial numbers are we to use for a description?) Only generally accepted varieties on paper money will be certified. Even though they might have come about as a result of an error, there existance is consistient enough to clasify it as such.
Hope that helped.
BCS