Review by Executive Director. Each name on the showing of interest forms shall be compared with the names on the employer list. Each valid showing of interest form shall be marked in the upper right hand corner in a suitable fashion to show it has been accepted. Each invalid showing of interest form shall be marked as: “NOL” if the name is not on the employer list; “Excluded” or with an abbreviation thereof if named by the employer as an excluded employee; or “Invalid” or with an abbreviation thereof if determined invalid by the Executive Director. Forms marked “excluded” or with an abbreviation shall indicate the employer’s stated reason for exclusion as follows: Managerial employee; Confidential employee; When excluded from the definition of public employee, a supervisory employee; or Other stated reason for exclusion. Forms marked “invalid” shall show the reason for invalidity as follows: Illegible; A duplicate showing of interest form for the same petitioner; Fraudulent; or Other stated reason for invalidity. If an employee files one showing of interest form for more than one exclusive representative, one form for each exclusive representative shall be valid if the showing of interest form otherwise complies with this subtitle. The number of accepted showing of interest forms shall be tabulated. If the Executive Director determines the showing of interest is not adequate, the Executive Director shall allow the petitioner a minimum of an additional 30 days to submit additional showing of interest forms after the petitioner is notified of the determination. Showing of interest forms are confidential and may not be released unless a petition is declared invalid. If a petition is declared invalid, the marked showing of interest forms shall be returned to the petitioner.