The correct title of this article is A# (.NET). The substitution or omission of the # is because of technical restrictions.
A# is a port of the Ada programming language to the Microsoft .NET platform. A# is freely distributed by the Department of Computer Science at the United States Air Force Academy as a service to the Ada community under the terms of the GNU General Public License.
AdaCore has taken over this development, and announced "GNAT for .NET", which is a fully supported .NET product with all of the features of A# and more.