Answer:
From the instructions to the FinCEN CTR:
Enter all zeros if the prior report DCN or BSA ID is unknown, for example when the prior report was a paper filing.
As a caution to others, I think any reviewer's presumption will be that this is for a form filed on paper as was the case here. My observation would be that the DCN from an electronically filed form is subject to a 5 year record retention requirement and the filer is obligated to have it; this is not a "get out of jail free" card.
First published on BankersOnline.com 4/8/13