A consume operation with the sse.log property and a single input field is a Log Consume, which can log SPARKL events. Use the same property on operations, services, mixes or folders to offer them, and their content, for logging.

A Log Consume does not have to be inside a mix folder.
<folder name="Scratch">
  <consume name="Log" 
    <prop name="sse.log"/>
<!-- Demo mixes should be inside the Scratch folder -->
Note: The Log consume operation above is by default loaded into your configuration tree. It is implemented by the Logger, a default logger service. Since no keys or sources are defined for it, the consume uses the default key and logs all types of events.