Similarly, the federal constitutional initiative allows citizens to put a constitutional amendment to a national vote, if 100,000 voters sign the proposed amendment within 18 months.[note 8] Parliament can supplement the proposed amendment with <answer>a counter-proposal</answer>, and then voters must indicate a preference on the ballot in case both proposals are accepted. Constitutional amendments, whether introduced by initiative or in Parliament, must be accepted by a double majority of the national popular vote and the cantonal popular votes.[note 9]
What can Parliament supplement the amendment proposed by the citizens with?
a counter-proposal