[Koha] Unique entries

[Lenora Oftedahl]

Ok.  I have barcode set up to be a unique entry (cannot be two barcodes with the same number).  But I can't remember how I did that, nor can I find instructions in the documentation.  MARC Framework, Newbie Guide, searching for Unique Entry in the wiki.
 
I know when someone tells me where to find the info, I'll be all like 'duh', but please help.
 
Lenora
StreamNet Regional Library
Columbia River Inter-Tribal Fish Commission