The main view at the top of the Deep Dive Perspective shows transactions, the events that make up those transactions, or metrics requested via the other views below. The description above this view includes the name of the RTI data set, how many transaction are in the date set and how many are currently visible (due to filtering). The table itself is (initially) the transaction table, which contains one entry for each "top-level" transaction that has been traced:
Deep Dive view showing all transactions
Each of these top-level transactions will typically consist of a number of events organized in a tree. You can examine the component events by either expanding the transaction by clicking on the expansion "triangle" at the very left, or by selecting the transaction, right-clicking, and selecting Focus On Transaction from the context menu. The table will switch to tree mode and display the component events.
Deep Dive view, focused on one transaction

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