This part of IEC 62351, which is a technical report, addresses the handling of access control of users and automated agents to data objects in power systems by means of role-based access control (RBAC) as defined in IEC TS 62351-8. IEC TS 62351-8 defines three different profiles to distribute role information and also defines a set of mandatory roles to be supported. Adoption of RBAC has shown that the defined mandatory roles are not always sufficient and it is recommended that the method for defining custom roles be standardized to ensure interoperability. Hence, the main focus of this document lies in developing a standardized method for defining and engineering custom roles, their role-to-right mappings and the corresponding infrastructure support needed to utilize these custom roles in power systems. This is achieved by defining categories and sub level categories, which provide a distinction of actions, connected with dedicated rights as well as a proposal for a format to distribute the custom role-to-right mappings. Moreover, a format is being proposed to distribute the information on custom defined roles and associated rights by utilizing XACML as an established standard for access control. Besides the discussion of handling custom roles, this document also addresses the following issues:
– Providing recommendations and/or examples for role-right-operation and (object) association to ensure interoperability from operational and developers point of view.
– Providing mechanisms and rules to avoid overloading of existing roles by allowing for an aligned way to define new (custom) roles.
– Easing the administration of roles in IEDs from a device management point of view:
   • Allowing for centralized assignment of roles, by maintaining the same associations    on device/application level.
   • Avoiding the definition of role-right-operation on command level to cope with diverse application environment of IEC TS 62351-8 (e.g. IED, substation level, control centre, SCADA).
– Enhancing available constraints for acting in a specific role considering the local environment with respect to operational constraints.dition 1.0 2018-01 TECHNICAL REPORT colour inside Power systems management and associated information exchange – Data and communications security – Part 90-1: Guidelines for handling role-based access control in power systems IEC TR 62351-90-1:2018-01(en) THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright ？ 2018 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of t