I guess every rule has some leniency.
As stated on the banknotecertification.com website:
Will my error note receive appropriate certification?
Error notes will not be certified. The variation in error notes is too broad and open to interpretation.
Source:
http://www.banknotecertification.com/faq.php#faq2
And then I had to go and find this online...
{http://img199.imageshack.us/img199/435/bcserror.jpg:http://img199.imageshack.us/img199/435/bcserror.th.jpg}
(item 390523406039 on that famous auction site if the above picture is not loading)