It's an innocuous-looking black-and-white notice - but its contents are explosive.

A circular issued in Bihar's Muzaffarpur District demands that all students in state-run schools indicate their caste on the answer sheets for their annual exams.

The circular says, "All those appearing for annual examination, please don't forget to mention whether you belong to a Scheduled Tribe, Scheduled Caste, Extreme Backward Caste or Other Backward Castes, for an honest assessment."

The official who issued the circular says the request for caste from children in Classes 1-8 should be lauded.

"This will help us find out how many students from each category appeared in the examinations... and what has been the academic performance of each category," states Shankar Kumar, Bihar Education Project Coordinator, Muzaffarpur District.

After the media began reporting on the circular, it was withdrawn, but there's no clarity on who asked for the census in the first place.

''We've ordered an inquiry, but no such order was issued by the State Government," defends Hari Narayan Singh, Human Resources Development Minister, Bihar.

The obvious: that this is another example of Bihar's obsession with caste. "If they start this at the school-level, they will marks students according to their caste. This is very wrong," says Satya, a member of the National Commission for Scheduled Castes.

We ask Anuradha, a student of Class 5, what caste means to her. ''We don't ask about caste. We study and play together," she says, sitting on a swing at a playground.

Many worry that so many children like her are being used to provide a database to politicians on the caste census for the district - information they are certain to use for elections of all sorts.