(1) An authorization card is proof of interest that must be submitted in support of a petition for certification. The card must contain the following:

(a) the employee's name, typed or legibly printed;

(b) the employee's signature;

(c) the date of the employee's signature, dated within six months of the date of the filing of the petition;

(d) a statement that the employee designates the named labor organization as the employee's exclusive representative for purposes of collective bargaining with the employee's employer; and

(e) if the card is submitted as proof of interest in support of a new unit determination petition for certification without an election, the card must also include a statement that the employee understands that the employee's signature may be used to obtain certification of the named labor organization as the exclusive bargaining representative without an election.

(2) The proof of interest submitted with any petition shall not be furnished to any of the parties. The board agent shall consider the adequacy of the showing of interest and such decision shall not be subject to challenge.