Section 1503 - Petitions to board; form and filing(a) All proceedings before the board or any referee, and all appeals to the board, shall be instituted by petition addressed to the board. All petitions shall be in writing and in the form prescribed by the board.(b) All petitions, all copies of agreements for compensation, and all papers requiring action by the board, shall be mailed or delivered to the department at its principal office.1939, June 21, P.L. 566, No. 284, § 403.