Definition Of Public Duty

Last year supreme court judgment (Ramesh Gelli vs CBI) in that Court dismissed hi criminal revision application stating that he is public servant u/s 46A of BR act, he hold an office as he was chairman of Global Trust Bank and also he was discharging public duty. My question is whether following person/institution covers public duty 1. Principal and Employees of Educational Institution without Govt Aid. 2. Director and employees of Private company listed with BSE and NSE where Govt indirectly hold less than 49% of share and other shareholder are General Public