Coordinate Management in the GeoDatabase
From Fmepedia
Check out this PDF document on the ESRI web site entitled Understanding Coordinate Management in the Geodatabase (http://support.esri.com/index.cfm?fa=knowledgebase.whitepapers.viewPaper&PID=17&MetaID=1301).
It's a great document to be aware of when migrating data from pre-v9.2 geodatabases.
