1 Pa. Code § 35.137
Witnesses shall be examined orally unless the testimony is taken by deposition as provided in §§ 35.145-35.152 (relating to depositions) or the facts are stipulated in the manner provided in § 35.112 (relating to conferences to expedite hearings) or in § 35.155 (relating to presentation and effect of stipulations) or the testimony is submitted in prepared written form as provided in § 35.138 (relating to expert witnesses). Witnesses whose testimony is to be taken shall be sworn, or shall affirm, before their testimony shall be deemed evidence in the proceeding or any questions are put to them.
1 Pa. Code § 35.137
This section cited in 4 Pa. Code §265.3 (relating to level II hearings); 12 Pa. Code §81.231 (relating to witness to be advised); 25 Pa. Code §1021.123 (relating to evidence); 34 Pa. Code §95.94 (relating to depositions); 34 Pa. Code §131.42 (relating to evidence relating to supersedeas); 34 Pa. Code §131.49 (relating to disposition of automatic request for special supersedeas under section 413(a.1) of the act (77 P. S. § 774(1)); 34 Pa. Code §131.53 (relating to procedures subsequent to the first hearing); 34 Pa. Code §131.53a (relating to consolidated hearing procedures); 34 Pa. Code §131.203 (relating to hearing procedures); 34 Pa. Code §131.204 (relating to UEGF subpoenas and interrogatories); 37 Pa. Code §123.10 (relating to testimony); 37 Pa. Code §171.96 (relating to arbitration hearing procedure); 37 Pa. Code §197.48 (relating to procedure at hearing); 37 Pa. Code §197.90 (relating to procedure at hearing); 51 Pa. Code §21.25 (relating to conduct of the hearing); 52 Pa. Code §5.411 (relating to oral examination); 52 Pa. Code §1005.151 (relating to oral examination); 58 Pa. Code §145.11 (relating to order of formal hearing); and 61 Pa. Code §703.34 (relating to hearing procedure).