Once, for a case, I searched in Web to find Guidelines by Indian Medical Association as to how Post-mortems are to be conducted by doctors. 
But I could not find any guidelines.
Value of Postmortem Report in Court
It is just an opinion of a doctor who  may have examined dead body of a victim. He may have written  down details in a format... But it is still an personal opinion. 
Another Doctor can always come in witness box to refute opinion given by Doctor who conducted post Mortem report.
What I am trying to say is this: 
1) There is no Form of Post Mortem  Report prescribed in Criminal Procedure Code.
2) There is no provision in Indian Evidence Act that whatever is said by a doctor or doctors in postmortem report shall be final. 
3) Every item in a postmortem report is subject counter evidence by other doctors.
4) Postmortem report is just a personal opinion of one doctor. 
Haresh Raichura
2/7/2014