Electronic filing requirement expanded to define who must file electronically and what documents may be omitted from electronic returns. The amendment prescribes that certain documents, statements, receipts, certificates or audited reports need not accompany the return but must be produced before the Assessing Officer on demand under section 139C, and it sets out the classes of persons required to furnish returns electronically, the form and manner of electronic returns, documents not to be furnished with electronic returns, and the computer resource or electronic record to which returns may be transmitted under section 139D.