Griffin Technology Final Vinyl 2.5 - Manual (Page 12)

AU Effects
In the provided Effects list, you will see many
names preceded by “AU.”
Audio Units (AU) are a set of Apple-designed
plug-ins provided by Core Audio in Mac OS X.
AU are used by Macintosh applications such as
GarageBand, SoundTrack Pro, Logic Express,
Logic Pro, Final Cut Pro, and most 3rd party
audio software developed for Mac OS X.
If you’d like more information on AU effects,
there is documentation on Apple’s website
that provides a list of the various Effect Units
and descriptions of what they do:
http://developer.apple.com/documentation/
MusicAudio/Conceptual/CoreAudioOverview/
SystemAudioUnits/chapter_951_section_1.html#/
/apple_ref/doc/uid/TP40003577-CH8-SW2