Bank c/c limit

I want to get C/C limit of Rs.40 lakh from SBI.

Is there any such condition that credit rating from CRISIL is manadatory?

I have come to know that this rating is calculated by bank on his own and not by customer?

Please suggest me about the truthfullness of the above facts.

REGARDS

In case of Exposer above 10 Lacs a Bank has to do credit rating of the applicant (Done by bank).

It is not required to be get done from CRISIL.