The operation of the "Telegram Retransmission System", described in Recommendation F.3 1, depends on the use of a standard format in telegrams. The format contains routing and other operational information in a heading part. This includes a four-letter “destination indicator”, which is one of the key elements used for routing a telegram at switching centres in the origin country, and in any transit country(ies). They are also used for routing in the destination country. Depending on the arrangements in individual centres, other elements used for automatic or manual routing include the origin indicator, the outgoing or incoming channel indicator and the office of destination. These elements are also used to provide the basis for the billing and accounting processes. For this and other operational reasons, the “F.3 1” format or its component parts are used when handling telegrams other than via the Telegram Retransmission System. Destination indicators have wide applicability.