In the following msdn link, there is 'event data' listed like Count, Depth, Reason .. http://msdn.microsoft.com/en-us/library/ff356162%28v=vs.100%29.aspx#gcstart_v1_event
According to this link, I created a .etl file. http://msdn.microsoft.com/en-us/library/dd264809.aspx
Using xprefview.exe I observed the etl file and even found the desired event 'GCStart_V1', looking at the column opcode in view 'summary table'.
Question: Where do I find the 'event data' that is listed in the first link?