This wait type is when a thread switches to preemptive mode as part of communicating with an OLE DB provider.
The map_key value in sys.dm_xe_map_values is 473 in 2008 and 2008 R2, 521 in 2012, and 537 in 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.