(a) Upon the filing of a valid petition, the General Counsel may request GAO to notify employees as to the existence of the petition by posting a notice for at least 10 days in locations appropriately selected to reach all employees in the unit covered by the petition. The notice shall include a request that the Board's General Counsel be notified of the existence of any other interested parties.

(b) GAO shall supply the General Counsel with any information in its possession concerning other potentially interested labor organizations, copies of relevant correspondence, and copies of existing or recently expired agreements covering any employees in the unit. The GAO shall also provide a list of employees it believes should be included in the unit together with their classifications and the names and classifications of those employees it proposes to exclude from the unit.

(c) All interested parties shall meet as soon as possible after the expiration of the 10-day posting period and shall attempt to resolve any issues in controversy.

(d) A labor organization may become an intervenor in any representation proceeding by submitting to the General Counsel, within the 10-day period, evidence that it represents at least 10 percent of the employees in the proposed unit or that it is the exclusive representative of the employees involved. Denial of a request to intervene may be appealed to the Board. Such an appeal must be filed within 10 days of service of the General Counsel's determination.