Mastering Tools from System 6000:

The MD3 Stereo Mastering package brings processing only known from the System 6000 to ProTools and PowerCore. This package presents professional production and mastering possibilities to the realm of DAWs, and integrates smoothly with serious music and film editing applications.
The MD3 Stereo Mastering package for ProTools and PowerCore includes two pristine algorithms, MD3 Multiband Dynamics and BrickWall Limiter:

MD3 Multiband Dynamics:

Dual Mono and Stereo dynamics processing in three frequency bands. By offering a true side-chain split structure, MD3 is also capable of demanding mono material compression/limiting on two separate channels, not found in other multi-band dynamics processors. MD3 can be regarded as a high-end mastering tool. M and S components of a stereo signal can be processed separately and provide even more control making full use of the Spectral Stereo Enhancer.

Brickwall Limiter:

If you are concerned about audio quality at the end listener, or have a desire to conserve talent, the BrickWall Limiter is the solution. While it cannot prevent destruction of dynamic range from happening at earlier stages in the production process, it does get rid of the signals known to generate distortion in consumer CD players, radio processors and data reduction codecs.