P.R. Laws Ap. tit. 32A, § III, Rule 41.3
The order of reference to the master may specify or limit his powers and may direct him to report only upon particular issues, or to do or perform particular acts, or to receive and report evidence only and may fix a reasonable time for the filing of the master’s report. Subject to the specifications and limitations stated in the order, the master has and shall exercise the power to regulate all proceedings in every hearing before him and to do all acts and take measures necessary or proper for the efficient performance of his duties under the order. He may require the production before him of evidence upon all matters embraced in the reference, including the production of all books, papers, vouchers, documents and writings applicable thereto. He may rule upon the admissibility of evidence unless otherwise directed by the order of reference, and shall have the authority to put witnesses on oath and may himself examine them and may call the parties to the action and examine them upon oath. When a party so requests, the master shall make a record of the evidence offered and excluded in the same manner and subject to the same limitations as provided in the Rules of Evidence.