CoreMIDI refers to the built in MIDI support available in Mac OS X. It allows for you to set up what devices are attached to any interfaces with Mac OS X drivers. You can assign device names and attributes such as which channels they can work with, and what other features they may support such as MIDI Clock and/or Machine control. CoreMIDI is basically a built in system that gives you the power and flexibility in your MIDI system as OMS and/or FreeMIDI does under OS 9. Another advantage is that currently any CoreMIDI enabled application under OS X can utilize MIDI Time Stamping (MTS) with any of the MOTU MIDI interfaces.