B. L. Yadav, J.

1. Whether the provisions of Rules 4 and 5 of the bihar Civil Service (Executive Branch)and the Bihar Junior Civil Service (Recruitment) Rules, 1951 (for short the Rules) are mandatory or directory and whether the Bihar Public Service commission (for short the Commission) could have made the advertisement only after indicating the number of vacancies in each services to be filled up, are the short but significant questions for our determination in the instant writ-petition filed by Subodh kumar and 40 others (who have appeared at the preliminary test conducted by the Commission) against the commission, Bailey Road, Patna, including the members of the Commission and the State of Bihar (for short the State) with a prayer that a writ in the nature of certiorari or any appropriate writ the issued quashing the result of the preliminary test of the 40th Combined Competitive Examination conducted by the Commission for appointment to the various posts and services in the State, and further for declaration that the preliminary test held pursuant to the advertisement dated 23rd April, 1995 is null and void and for issuance of a writ of mandamus commanding the responde