In the "UI Examples" App, the following comment can usually be found.
<!-- tells the addterm intention to put our term in the first search clause no matter what. -->
<param name="flags"><list>indexed</list></param>
In the next search command, what is the first search clause?
index=_internal source=*metrics.log | chart sum(kb) by series | sort -sum(kb) | search series=audit*
The stuff before the first pipe, i.e. index=_internal source=*metrics.log
The stuff before the first pipe, i.e. index=_internal source=*metrics.log