This specification defines the APIs that an Operator Platform would use for the realisation of its Southbound Interface to the Operation, Administration and Maintenance Functions. This initial version of the specification focusses on the APIs to support the lifecycle management of network slicing to support the Operator Platform’s Network Slicing as a Service capabilities. The APIs covered for this interface are mostly defined by 3GPP’s Management and Orchestration capabilities. This specification defines a baseline for the APIs that are expected to be supported to enable the Operator Platform use cases. This initial version of the specification is aligned with the requirements in GSMA PRD OPG.02 v5.0.