True to the Pareto Principle, 80% or more of the work in any Peoplesoft module can be done by knowing just 20% (or far lesser) of the tables in the system. But it's real exciting to explore and look at the rest of the infrequently used tables as most of them will have a very specific purpose which might come to light only under certain rare occassions. One such table is TL_XREF_TBL.
Where is it used?
The XREF table plays a critical part in the integration of Time and Labor and North American Payroll. When Payable Time is loaded from the TL_PAYABLE_TIME table to the paysheets in North American Payroll, the load program consolidates payable time entries before sending to NA Payroll. Consolidation means that the quantity for each TRC is summed up and a single entry with the aggregate quantity is sent to NA Payroll for each TRC under the period in question. During this process, the system assigns a cross reference number (XREF_NUM) to all the consolidated entries of a single TRC. The TL_XREF_TBL stores the XREF_NUM corresponding to each sequence number on the payable time table. The NA Payroll table PS_PAY_OTH_EARNS also contains a filed called XREF_NUM which can be used to find out the pay line entries corresponding to the spefic data that came from time and labor.
What is the practical utility of the table?
For most parts the XREF table is a background table which a developer may never need to use. But it will be very useful to audit the data flow between Time and Labor and N A Payroll. I have used this in scenarios where customers have reported issues with payable time data not coming over to payroll. In this case, the link between payable time entries and paysheet entries can be drawn to the minutest detail using the XREF_NUM.