10.—(1) Where a contracting authority intends to award a public contract on the basis of the offer which is the most economically advantageous in accordance with regulation 30(1)(a), it must indicate in the contract notice whether or not it authorises economic operators to submit offers which contain variants on the requirements specified in the contract documents and a contracting authority must not accept an offer which contains a variant without that indication.
(2) Where a contracting authority authorises a variant in accordance with paragraph (1) it must state in the contract documents the minimum requirements to be met by the variant and any specific requirements for the presentation of an offer which contains variants.
(3) A contracting authority must only consider variants which meet its minimum requirements as stated in the contract documents in accordance with paragraph (2).
(4) A contracting authority must not reject an offer which contains variants on the requirements specified in the contract documents on the ground that—
(a)where it intends to award a public services contract, the offer would lead to the award of a public supply contract; or
(b)where it intends to award a public supply contract, the offer would lead to the award of a public services contract.