If a resource did not have an identifiable Sublibrary/Collection during the migration from Advance to Aleph, its Aleph location will be MISC BLANK. Bill and Corey need to do some analysis and may be able to "fix" some of them algorithmically. If you encounter a record with a MISC BLANK in the course of your daily work, you should probably leave it alone. If the item in hand is clearly a new location/copy, you may add a new location/copy to the record. If it is not known if the item in hand is the MISC BLANK location/copy, please set it aside until the analysis and fix is done. If you absolutely know you've got the MISC BLANK in hand and you can fix it, if's probably ok to do that. The last thing you want to do is add a new correct holdings/item that represents the same object as the MISC BLANK location.
Are you confused yet? There are only 2500 or so of these MISC BLANK holdings in Aleph so you may not ever encounter one. If you want to see one, the following records have MISC BLANK locations: 350831, 1623532, 556477, 10241, 34578, 29267, 653422. Or you can do a CCL search if you know the right index.