Section 621 - Appeals to appeal board1. Disputed claims for benefits. Within twenty days after the mailing or personal delivery of notice of the decision of a referee on contested benefit claims, the claimant and the employer, provided he appeared at the hearing, may appeal to the appeal board by filing a notice of appeal in the local state employment office in accordance with such rules as the appeal board shall prescribe. Within the same period of time and in the same manner, the commissioner may also appeal to the appeal board, regardless of whether or not he appeared or was represented at the hearing before the referee.2. Contested determinations, rules, or orders. Within twenty days after the mailing or personal delivery of notice of the decision after a hearing on contested determinations, rules or orders by the commissioner, the employer may take an appeal to the appeal board, provided he appeared at the hearing, by filing a notice of appeal with the commissioner, and the commissioner may likewise within such period take an appeal to the board by giving written notice thereof to the employer, regardless of whether or not the commissioner appeared or was represented at the hearing before the referee.3. Conduct of appeals. The appeal board may decide any case appealed to it under any provision of this article on the basis of the record and of evidence previously submitted in such case, or it may in its discretion hear argument or hold a further hearing, or remand such case to a referee for such purposes as it may direct. If a further hearing is to be held or argument had, the board shall fix a time therefor and shall notify the commissioner, regardless of whether or not he had appeared or been represented at the hearing before the referee, and any other party affected, provided such other party appeared at the hearing before the referee. The board may affirm or reverse, wholly or in part, or may modify the decision appealed from and shall render its decision promptly and shall thereupon send written notice thereof together with the reasons therefor to the commissioner and any other party affected thereby who appeared at the hearing before the referee.