Here's some visuals of a spark table, a PE spark adder table, and an EGR spark adder table. They are not for your vehicle, but may help with understanding the functionality of what I mentioned earlier.
Newer vehicles have a fairly complex adaptive spark logic with several other extra spark tables that include things like "low-octane spark", and "high octane spark".
Here, the bottom 2-Dimension table is the spark adder for EGR, or "Spark added vs %EGR". The top table is the VE compensation table.
http://i702.photobucket.com/albums/w...EGRscreen1.jpg
Next is another 3-dimensional main spark table (from a different vehicle) and a smaller 2-dimensional PE (Power Enrichment) spark adder table. It shows spark added when increased load is triggering Power-Enrichment mode of operation for added fuel delivery.
http://carphotos.cardomain.com/ride_...0082_large.jpg
There is some further explanation of EGR operation here in this thread on Ecomodder:
http://ecomodder.com/forum/showthrea...e-7358-17.html