Related: http://stackoverflow.com/questions/13508162/is-there-a-way-to-change-the-values-for-fixedlennullinsource-and-trimtrailingbla (the answer shows the definition), note that the [Microsoft documentation](https://msdn.microsoft.com/en-us/library/ms187335%28v=sql.110%29.aspx) says it is for backwards compatibility only. So other than academic curiosity, you shouldn't really care about its value.
– Mark RotteveelJun 27 '15 at 07:30