Roll certification question

smokincoin

Sorry if this has already been discused. I'm wondering if they look at all the coins individually or simply transfer the roll? I think it'd be cool, but probably impossible to complete, to have a collection of Lincolns in these! Pcgs
edited to add the "?" mark.

FLBuffaloHunter

My guess is they are coins that did not meet the minimum grade on a bulk submission. The submitter has the option of having those coins placed in a 'BU' certified roll in lieu of having the coins returned.