72 Pa. Stat. § 5020-501
The county commissioners of each county of the fourth, fifth, sixth, seventh and eighth classes shall compose a board to be called a "Board of Revision," of which the county commissioner holding the oldest certificate of election shall be the president. The members of said board shall each take and subscribe an oath or affirmation, before the president of the court of common pleas, the prothonotary, or any of the associate judges of the county, in the following words, to wit: "I ... do swear or affirm that I will faithfully, and to the best of my knowledge and judgment, revise, correct and equalize the valuation of all property taxable by law ... in ... county, ... and faithfully perform all the duties of a member of the board of revision for ... county, according to the laws of this Commonwealth,"--which oath shall be deposited in the office of the recorder of the county.
72 P.S. § 5020-501