(a) Rulings of Board employees, including administrative law judges, may be appealed prior to service of the initial decision only if:

(1) The ruling denies or terminates any person's participation;

(2) The ruling grants a request for the inspection of documents not ordinarily available for public inspection;

(3) The ruling overrules an objection based on privilege, the result of which ruling is to require the presentation of testimony or documents; or

(4) The ruling may result in substantial irreparable harm, substantial detriment to the public interest, or undue prejudice to a party.

(b) In stand-alone cost complaints or in cases filed under the simplified standards, any interlocutory appeal of a ruling shall be filed with the Board within three (3) business days of the ruling. Replies to any interlocutory appeal shall be filed with the Board within three (3) business days after the filing of any such appeal. In all other cases, interlocutory appeals shall be filed with the Board within seven (7) calendar days of the ruling and replies to interlocutory appeals shall be filed with Board within seven (7) calendar days after the filing of any such appeal as computed under 49 CFR 1104.7.