The SMETS1 Supporting Requirements (S1SR) document describes the supplementary rules for how DCC will process SMETS1 Service Requests / Service Reference Variants (SRs/SRVs) and includes the accommodation of behaviours that are specific to particular SMETS1 Device Models. DCC has concluded on its consultation of 14 September 2021, on further changes to the S1SR, which consultation closed on 28 September 2021.