The purpose of the language requiring a party participating in an arbitration proceeding to raise an objection that no arbitration agreement exists "not later than the beginning of the arbitration hearing" is to insure that the party makes a timely objection at the start of the arbitration hearing rather than causing the other parties to go through the time and expense of the arbitration hearing only to raise the objection for the first time later in the arbitration process or in a motion to vacate an award. A person who refuses to participate in or appear at an arbitration proceeding retains the right to challenge the validity of an award on the ground that there was no arbitration agreement in a motion to vacate.

3. Section 23(a)(6) is a new ground of vacatur related to improper notice as to the initiation of the arbitration proceeding under Section 9. The notice requirement in Section 9 is a minimal one intended to meet due process concerns by informing a person as to the controversy and remedy sought. The notice of initiation of the arbitration proceeding is also subject to reasonable variation by the parties' agreement. See Section 4(b)(2).

4. The notice of initiation of arbitration is not intended to be a formal pleading requirement. Thus, a party may waive the objection in Section 9(b) by failing to make a timely objection. Section 23(a)(6) also requires that there is substantial prejudice to the other party before a court vacates an award for improper notice of initiation.

5. If a court orders a rehearing, Section 23(c) provides that the arbitrator must "render the decision in the rehearing