Final answer:
The summariesonly=t argument results in only the summaries of tsidx files being displayed, which provides quick reference without the full contents.
Step-by-step explanation:
When using the summariesonly=t argument in the context of tsidx files, it instructs the system to display only the summaries of the tsidx files. The tsidx (Time Series Index) files are used by indexing engines such as Splunk to rapidly retrieve events for search results. With the summariesonly parameter set to true, the output will not include the full contents of the tsidx files, but rather just the summaries, which provide quick reference to the data structure instead of detailed data.