(a) Witnesses appearing at the hearing need not be sworn. The administrative law judge may, however, within his discretion, require that witnesses take an oath or affirmation as to testimony submitted.

(b) Written statements may be filed any time prior to the date of the hearing by persons who cannot appear personally.

(c) Written documents and exhibits shall be tendered in quadruplicate. When evidence is embraced in a document containing matter not intended to be put in evidence, within the discretion of the administrative law judge, such a document will not be received but the person offering the same may present to the administrative law judge the original document together with two copies of those portions of the document intended to be put in evidence.

(d) At any stage of the hearing, the administrative law judge may call for further evidence upon any matter. After the hearing has been closed, no further evidence shall be taken, except at the request of the Administrative Review Board, unless provision has been made at the hearing for the later receipt of such evidence. In the event that the Administrative Review Board shall cause the hearing to be reopened for the purpose of receiving further evidence, due and reasonable notice of the time and place fixed for such taking of testimony shall be given to all persons who have appeared at the hearing or filed a notice of intention to appear at the hearing.

(e) The rules of evidence prevailing in courts of law or equity shall not be controlling. However, it shall be the policy to exclude irrelevant, immaterial, or unduly repetitious evidence.