The board shall issue a certificate certifying as a professional librarian any person who requests certification upon a form prescribed by the board and who fulfills one or both of the following requirements:—

1. (1) Graduation from a library school accredited by the American Library Association or the passing of an examination which, with due consideration of education, professional training, practical experience and demonstrated ability, shall satisfy the board that the candidate has the qualifications required for the satisfactory practice of library work.

2. (2) The holding of an unexpired certificate issued by the proper authority in any state other than this commonwealth in which the requirements for certification are satisfactory to the board.

   The board shall issue a certificate certifying as a sub-professional librarian any person who requests certification upon a form prescribed by the board and who, in the opinion of the board, is qualified to practice library work in a position not requiring the educational and other qualifications for certification as a professional librarian.