(a) Oral or written communications which relate solely to matters which the Hearing Officer, Regional Director, Administrative Law Judge, General Counsel or member of the Board is authorized by law or Board rules to entertain or dispose of on an ex parte basis;

(b) Oral or written requests for information solely with respect to the status of a proceeding;

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

(d) Oral or written communications proposing settlement or an agreement for disposition of any or all issues in the proceeding;

(e) Oral or written communications which concern matters of general significance to the field of labor-management relations or administrative practice and which are not specifically related to any agency proceeding subject to 5 U.S.C. 557(a); or

(f) Oral or written communications from the General Counsel to the Board when the General Counsel is acting on behalf of the Board under 22 U.S.C. 4109(d).