Lost-Data Indicator

When SNA Server sends RTM data to the host, it can indicate to the host that RTM data may have been lost (that is, some host response times were not included in the RTM data sent to the host). This indication is sent in the following cases:

One of the RTM counters reaches its maximum value, and SNA Server is not configured to send RTM data unsolicited at counter overflow. When this occurs, SNA Server stops recording response times until the host requests the data (or until end-of-session, if unsolicited sending at end-of-session is configured); the data is sent with an indication that data may have been lost due to counter overflow.
When the local server terminates abnormally, RTM data obviously is lost and any connection to the host is terminated. When the connection to the host is started, there is no way of knowing whether the connection was previously terminated by a server failure; therefore, the first RTM data sent to the host after the connection is established includes the lost-data indicator, to indicate that data may have been lost due to failure of the local server.
When SNA Server is configured to send RTM data at end-of-session, and a new 3270 session is started before the RTM data for the previous 3270 session on the same LU can be sent, response times for the new session are discarded until the RTM data from the previous session is sent and the counters are reset. When RTM data is next sent on the new session, it includes the lost data indicator to indicate this condition.