A revision and extension of Ada (Ada 83) begun in 1988 and completed on 1994-12-01 by a team lead by Tucker Taft of Intermetrics. Chris Anderson was the Project Manager. The printed standard was expected to be available around 1995-02-15.
Additions include object-orientation (tagged types, abstract types and class-wide types), hierarchical libraries and synchronisation with shared data (protected types) similar to Orca. It lacks multiple inheritance but supports the construction of multiple inheritance type hierarchies through the use of generics and type composition.
GNAT aims to be a free implementation of Ada 95.
You can get the standard from the Ada Joint Program Office.
["Introducing Ada 9X", J.G.P. Barnes, Feb 1993].