A petition for the election of an exclusive representative of a bargaining unit may be filed with the Board by: an employee organization seeking certification as an exclusive representative; or an employee, a group of employees, or an employee organization seeking a new election to determine an exclusive representative. A petition shall: contain the information the Board requires; and be accompanied by showing of interest forms from 30% of the employees in the appropriate unit indicating their desire to be exclusively represented by the exclusive representative named in the petition for the purpose of collective bargaining. If the Board determines that a required showing of interest is not adequate, the Board: shall allow at a minimum an additional 30 days for the petitioner to submit additional showing of interest forms after the petitioner is notified of the determination; and may, for good cause, provide additional time to the petitioner to provide additional forms. If a petition is supported by more than 50% of the public employees in the bargaining unit, the public employer shall immediately recognize the employee organization as the exclusive representative and afford to the exclusive representative and its members all rights due under this title. A petition filed under subsection (a) of this section shall include showing of interest forms provided to the Board from an employee organization. The Board shall accept a showing of interest form whether or not the signatures on the form are electronic or handwritten. For an election that is conducted to determine whether an exclusive representative should represent a unit, a showing of interest form is valid if the signatures were collected within the 18–month period immediately preceding the date on which a petition for the election is filed. For an election that is conducted to determine whether an exclusive representative should no longer represent a unit, a showing of interest form is valid if the signatures were collected within the 9–month period immediately preceding the date on which the petition for election is filed. A showing of interest form may be used by a public employee for each public employer that employs the public employee. Subject to paragraph (2) of this subsection, a public employer shall provide to the Board and the employee organization an alphabetical list of public employees in each bargaining unit within 2 days after a petition for an election is filed. The list required to be provided under paragraph (1) of this subsection shall: include for each public employee on the payroll for the last pay period before a petition for election is filed, the public employee’s: name; position classification; home and work site addresses where the employee receives interoffice or United States mail; home and work site telephone numbers; personal cell phone number; and work e–mail address; and identify each public employee that should be excluded as an eligible voter with a statement explaining the reason for the exclusion. A public employer may not challenge the eligibility of a public employee’s vote in an election if the employer fails to explain as required under paragraph (2) of this subsection the reason for excluding a public employee under this subsection. On application by a public employer or an employee organization, the Board may determine that a public employer shall be designated as a joint public employer of a public employee within a bargaining unit under this subtitle when the designation would best effectuate the purposes of this title.