This specification defines version 2.1 of OCPP. Version 2.1 is an extension of OCPP 2.0.1. OCPP 2.1 has its own JSON schemas, but the schemas are OCPP 2.0.1 schemas that have been extended with optional fields that are used by OCPP 2.1 functionality. With the minor exceptions mentioned below, all application logic developed for OCPP 2.0.1 will continue to work in OCPP 2.1 without any changes. The new features of OCPP 2.1, of course, require new application logic. Use case A02 & A03 The application logic in a CSMS for OCPP 2.0.1 for use cases A02 & A03 requires a small change in order to work in OCPP 2.1. The SignCertificateRequest message has been extended with a requestId field, such that the resulting CertificateSignedRequest message can be accurately mapped to the request that initiated it. Use of requestId is optional for Charging Station, but when present, CSMS will have to use it in the subsequent CertificateSignedRequest message. Note, that the updated application logic remains valid to use in OCPP 2.0.1. Use case N02 The application logic in a Charging Station for OCPP 2.0.1 for use case N02 requires a small change in order to work for OCPP 2.1. The message NotifyMonitoringReportRequest has been extended with a required field in VariableMonitoringType: eventNotificationType. Charging Station has to provide this field. It provides essential information to CSMS about the type of monitor (HardWiredMonitor, PreconfiguredMonitor, CustomMonitor) that was missing in OCPP 2.0.1. Existing OCPP 2.0.1 logic in a CSMS that is not aware of this new field, will continue to work.