premise: The Receiving Party shall immediately on request by the Disclosing Party return all or any part of the Confidential Information as shall be determined by the Disclosing Party and shall (at the Disclosing Party's option) - (a) return all copies and extracts of the Confidential Information and all summaries, reports and notes made that relate to or use the Confidential Information (whether on paper, in an electronic information storage and retrieval system, in any other storage and retrieval system, or in any other storage medium); or (b) certify by letter signed by an authorized signatory of the Receiving Party that the items referred to in clause .6.1(a) have been destroyed or erased; or (c) do both of clauses 6.1(a) and 6.1(b) above. except that one copy of each may be retained by the Receiving Party's legal department for archival purposes only.