Hi Eitan,
I'm sorry to disappoint you, but all three terms (or so) are no longer supported by NAV2013.
N/ODBC: That would be C/ODBC (nodbc is a driver, no open interface): This was the ODBC driver for the "native" database of NAV. NAV2013 only works on SQL Server. You have direct access to the SQL database (with all pros and cons, but the benefit far outhweighs the problems).
C/OCX: OCX (ActiveX) interface. No longer supported in NAV2013. Your interface is .net Interop now.
C/FRONT: libc interface for NAV, no longer supported in NAV2013. Your interface is .net Interop now.
You have a few more interfacing capabilities, most useful is Web Services. There are quite a few blogs on utilizing web services. It is a powerful tool for building interfaces.
with best regards
Jens