Dynamic non-interactive tracing allows the collection of designated status data (such as PSW, registers, cross memory mode, etc) and designated storage areas for a total of 2K at designated trace points.
Grouping allows any number of tasks under any number of address spaces to be grouped into a single diagnostic unit.
The Remote Debug Facility allows the recording of a debug session including any trace points and group member data so that a recorded session could be sent offsite, executed, and the collected data sent back to the programmer.
In z/OS 1.13 and above, about half of the TDF system code can reside above the bar.