http://docs.safe.com/fme/html/FME_ReadersWriters/Default.htm#geodatabase/Writer_Directives_EntGeodb.htm
To figure out what the parameter setting: Validata Features to Write does. However I can not see any documentation on it. I "assume" it will only write Valid Features to the database (ie - features that have all Attributes) and that it will FAIL and ROLL BACK once it meets a feature which misses an Attribute in the feature (that is not null)
