29 CFR 1208.4: Material relating to representation function.

(a) The documents constituting the record of a case, such as the notices of hearing, motions, rulings, findings upon investigation, determinations of craft or class, dismissals, withdrawals, and certifications, are matters of official record and shall be made available on the NMB's Web site.

(b) This part notwithstanding, the NMB will treat as confidential evidence submitted in connection with the showing of interest in a representation dispute, including authorization cards and signature samples, and other personally identifying information received during an investigation.