what is cl and ncl for obc and what is the criteria for obc candidate. if father is govt job and appinted in clerk. i will get benefit of obc or not

thank u sir,  but  i have read some where if  father is appointed directly by class 1  or 2 officer they are not eligible if  he is appointed in class 3 or  4 and at the age of 45-50  if income is  6 lakhs  he is  eligible . is it true.  kindly help for my daughter