This is one of the legacy system. We need to migrate it immediately. For our new system we will definitely consider this suggestion. I understand start of the week can be modified by using locale settings config file. Any such configuration change can make this happen?

Both the versions provide week numbers in the range of 1-53. Actually this is nothing to with OBIEE10g to OBIEE11g. What I see here is that it is not matching the ISO week number