A supplemental Call for Proposals for stand-alone ACA projects was first issued during Cycle 6, but this was handled without any changes to the OT. From Cycle 7, however, the OT released as part of the submission of Phase-2 Science Goals (usually released at the end of July) will also be configured such that a dedicated ACA Supplemental Call proposal can be created which enforces specific restrictions e.g. only stand-alone ACA observations can be requested, no Large Programs, etc. Distributed Peer Review is used for all Supplemental Call proposals and thus reviewer information must be added. As with the normal Call for Proposals, there will be a submission time window defined on the server and only during this will it be possible to submit ACA Supplemental Call proposals.
ACA Supplemental Call proposals are distinguishable from the other types in that the editor panels are highlighted with a different colour (approximately cyan by default) and the proposal submission code uses the number '2' as the subcycle i.e. the first ACA Supplemental Call proposal of Cycle 7 had the code 2019.2.00001.S.