[Koha] Weeding

Hello, We have been on Koha 3.0 for a few months now and our libraries need to weed items. When was the 'Withdraw' authorized value added to Koha and more to the point, what is the purpose of this button at /catalogue/moredetail.pl? We are interested in hearing best practices for weeding items and permanently deleting them from the catalog (in 3.0). Sharon Moreland NExpress Shared Catalog