No stipulation or agreement between the parties, their attorneys, or representatives shall be enforceable unless it has been reduced to writing and signed by the parties or their authorized representatives, or unless dictated into the record during the course of a hearing, or incorporated into an order bearing written approval of all parties. This section shall not limit a party's ability to waive, modify, or stipulate any right or privilege afforded by these sections, unless otherwise precluded by law.
31 Tex. Admin. Code § 17.5