Source document number in er1, er3

Sumant T Hegde (CA Final Student) (85 Points)

10 July 2012  

Can any one explain what should be entered in Source document Number for Interest Payment in ER 1 or ER 3.

I heard that it is Excise registration number_ER1/ER3_period for which interest is paid.

Even if i put the correct details the error will come. So please explain in detail about the Source document No.