The topic "Derby support for SQL-92 features" in the Reference Manual (http://db.apache.org/derby/docs/10.10/ref/rrefsql9241891.html) seems not to have been substantively updated since about 2007.
For one thing, the parenthesis "(non-deferrable)" needs to be removed from Table 8 (constraint support). Also, I think we've supported natural joins for some time.
Could someone more knowledgeable than I am go through the items marked "No" and see if any more need updating? I think those two might be the only ones, but I am not quite sure.