# Mainframe Logger Data Streams

When using mainframe logger, three different streams ("LOG", "TRACE" and "STATISTICS") should be defined.

1. LOG: It is used to write formatted, documented and structured application messages. Log stream corresponds to the Substation ES JES default file - TIBLOGPR. User applications can write to this data stream.
2. TRACE: It is used to write trace messages when tracing levels are higher than zero (0). Substation ES and other TIBCO applications can write unformatted, undocumented, and unstructured tracing information to this stream. TRACE stream is used to contain memory areas and useful debugging information that is mainly understood by TIBCO personnel.

   Trace stream corresponds to the Substation ES JES default file - TIBTRCPR.

3. STATISTICS: It is used to write statistical events and messages. User applications can write to this data stream.

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