Patents As of March 31, 2007 we had 41 issued U.S. patents assigned to us. We also have a number of foreign patents, a number of U.S. and foreign patents pending, and we have licensed patents from others. Our technology is protected by more than 100 patents worldwide either issued, pending or licensed from others. We are continuing to develop inventions and expect to add to our patent portfolio. There are no patents we regard as critical to our business owned by us or licensed to us that expire in the next 12 months.
Much of our intellectual property has been developed with U.S. Government support. In accordance with federal legislation, companies normally may retain the principal worldwide patent rights to any invention developed with U.S. Government support.
Certain of our patents cover MRAM cells with transistor selection for data retrieval, which we believe may be necessary for successful high-density, high-performance MRAMs. We believe our 6,275,411 and 6,349,053 U.S. patents, both titled �Spin Dependent Tunneling Memory,� are particularly important. Both patents cover MRAMs using arrays of Spin Dependent Tunnel Junctions. Based on their public disclosures, we believe several companies are pursuing the approach described in these patents. The 6,275,411 patent expires in 2019 and the 6,349,053 patent expires in 2021. We also have patents on advanced MRAM designs that we believe are important, including patents that relate to magnetothermal MRAM, spin-momentum MRAM, and synthetic antiferromagnetic storage.