(a) Which relate solely to matters which the Hearing Officer, Regional Director, Administrative Law Judge, or Board Member is authorized by law or Board Rules to entertain or dispose of on an ex parte basis.

(b) For information solely with respect to the status of a proceeding.

(c) Which all the parties to the proceeding agree, or which the responsible official formally rules, may be made on an ex parte basis.

(d) Proposing settlement or an agreement for disposition of any or all issues in the proceeding.

(e) Which concern matters of general significance to the field of labor-management relations or administrative practice and which are not specifically related to pending on-the-record proceedings.

(f) From the General Counsel to the Board when the General Counsel is acting as counsel for the Board.