Dear Sourabh,
I am amazed with such a strange question you got,
As of my bookish as well the practical knowledge NO Accounting standard or accounting policy has stated that narration is mandatory..........
and many of the accountants including CA's are stating such an opinion which even Luca pacioli in the first book of accounting Summa de arithmetica, geometria, proportioni et proportionalità narration is compulsory
according to him he just said that the transaction can be explained with the help of narration.
But how ever as per the commercial as per the exam practices it is made like narration will be considered sooooo as of my opinion narration fetches you the information as per practical stituation and marks as per exams