[Metadatalibrarians] Non-MARC records

[Homa Faridi]

 Hello metadatalibrarians,

We are about to change our library system to Millennium, but before doing
so, we have to know whether we've got any "Non-MARC" records in our OPAC. I
searched for these records on Google and got nothing useful, I was wondering
how a non-MARC record really look like.

I figured out that some fields (maybe because of importing them from other
library catalogs) may not be MARC 21 standard fields like 886 (foreign MARC
field) and 887 (non-MARC field), but does this mean that any records which
include such fields, are considered as a non-MARC record and will be
rejected or transmitted faultily to the new system?
Can you give me more information on this field (non-MARC and foreign MARC
vs. MARC)? And let me know if there are anyways to solve this issue before
starting the conversion.

Are there any ways to figure out if we have got any non-MARC records in our
current system?

All the best,
H.F.