[OPENGL] Difference between ARB_texture_compression and EXT

[Lowercase]

Can someone explain the difference between these 2 extensions: EXT_texture_ compression_s3tc and ARB_texture_compression.

I heard s3tc is not patent free ? is it true ?

thanks..

[noeska]

have a look here for details: http://www.opengl.org/registry/

nb there are even more ext for texture compression

[Lowercase]

IP Status

Contact S3 Incorporated (http://www.s3.com) regarding any intellectual
property issues associated with implementing this extension.

WARNING: Vendors able to support S3TC texture compression in Direct3D
drivers do not necessarily have the right to use the same functionality in
OpenGL.

I'm not sure at all that now S3.com belongs to the graphic card manufacturer, http://www.s3.com/about/history.php.

Is there a small howto anywhere ?