SecurityKeyServices is an array of the DataType EndpointDescription and defines one or more Security Key Servers (SKS) that manage the security keys for the SecurityGroup assigned to the PubSubGroup. The EndpointDescription DataType is defined in OPC 10000-4.
The parameter is null if the SecurityMode is NONE_1.
Each element in the array is an Endpoint for an SKS that can supply the security keys for the SecurityGroupId. Multiple Endpoints exist because an SKS may support multiple transport profiles and/or may have multiple redundant instances. The UserTokenPolicies in each Endpoint specify what user credentials are required. OPC 10000-4 describes UserTokenPolicies in more detail.