Where an agency proposes to consider the exercise of authority to promulgate a regulation, it may conduct or give interested persons an opportunity to participate in a public evidentiary proceeding; and the agency shall always do so where the basic law requires a hearing. Evidentiary hearings may be limited to the trial of factual issues directly related to the legal validity of the proposed regulation in any of the relevant respects outlined in § 2.2-4027. General notice of the proceedings shall be published as prescribed in § 2.2-4007.03. In addition, where the proposed regulation is to be addressed to named persons, the latter shall (i) also be given the same notice individually by mail or otherwise if acknowledged in writing and (ii) be entitled to be accompanied by and represented by counsel or other representative. The proceedings may be conducted separately from, and in any event the record thereof shall be separate from, any other or additional proceedings the agency may choose or be required to conduct for the reception of general data, views, and argument pursuant to § 2.2-4007.02 or otherwise. Any probative evidence may be received except that the agency shall as a matter of efficiency exclude irrelevant, immaterial, insubstantial, privileged, or repetitive proofs, and may deny rebuttal, or cross-examination. Testimony may be admitted in written form provided those who have prepared it are made available for examination in person. The agency or one or more of its subordinates specially designated for the purpose shall preside at the taking of evidence and may administer oaths and affirmations. The proceedings shall be recorded verbatim and the record thereof shall be made available to interested persons for transcription at their expense or, if transcribed by or for the agency, for inspection or purchase at cost. Where subordinates preside at the taking of the evidence, they shall report their recommendations and proposed findings and conclusions that shall be made available upon request to the participants in the taking of evidence as well as other interested persons and serve as a basis for exceptions, briefs, or oral argument to the agency itself. Whether or not subordinates take the evidence, after opportunity for the submittal of briefs on request and such oral argument as may be scheduled, the agency may settle the terms of the regulation and shall promulgate it only upon (a) its findings of fact based upon the record of evidence made pursuant to this section and facts of which judicial notice may be taken, (b) statements of basis and purpose as well as comment upon data received in any informational proceedings held under § 2.2-4007.03 and (c) the conclusions required by the terms of the basic law under which the agency is operating.