This part of IEC 61850 specifies a method of exchanging data through any kinds of network, including public networks. Among the various kinds of services specified in the IEC 61850-7-2 only the client/server and time synchronization services are considered so far. For the client/server services, the principle is to map the objects and services of the ACSI (Abstract Communication Service Interface defined in IEC 61850-7-2) to XML messages transported over XMPP. The mapping description includes mainly three aspects: " The usage of the XMPP protocol itself, describing in details which features are really used and how they are used by the mapping (see chapter 6). " How to achieve end-to-end secured communications (see chapter 8). " The description of the XML payloads corresponding to each ACSI service thanks in particular to the XML Schema and XML message examples (starting at chapter 10). NOTE 1 This document does not address the detailed usage of the XMPP protocol. NOTE 2 This document doesn t address system management services. NOTE 3 For the information of people familiar with the mapping defined in IEC 61850-8-1, the XML messages defined in the present document are derived from those defined in IEC 61850-8-1 but with an XML encoding instead of a binary one. In this way implementing gateways between IEC 61850-8-1 and IEC 61850-8-2 is very straightforward in both directions. However reading the IEC 61850-8-1 document is not necessary to understand the present one.