Any offer of proof made in connection with an objection taken to any ruling of the Board rejecting or excluding proffered oral testimony, shall consist of a statement for the record of the substance of the evidence which the person contends would be adduced by that testimony.
If the excluded evidence consists of evidence in written form, or reference to documents or records, a copy of that written evidence shall be marked for identification and shall constitute the offer of proof.
D.C. Mun. Regs. tit. 10, r. 10-B3009