Apple Logic Express 8 - Manual (Page 690)

690 Chapter 32 Transposition With the Chord and Transposition Tracks
How MIDI Events and Apple Loops Are Transposed
Transposition events (and their chord counterparts) pitch-shift MIDI events and Apple
Loops.
MIDI Events
Transposition events change the actual MIDI events themselves. As an example: If you
create a MIDI region that contains a C3 note event, copy the MIDI region, and then
create a transposition event of +2 at the start of the copied MIDI region, the
transposition event changes the note event to a D3.
Despite this data change to events, the Transposition track works non-destructively, as
you can change the transposition of MIDI events multiple times. Imagine that you
copied the D3 of the example above to a position where the Transposition track is set
to +2; the MIDI event will by played back as D3. But if the Transposition track is set to a
different playback interval at the target position, the MIDI event will be pitch-shifted to
the new playback transposition.
Transposition events only affect MIDI events already in your project. They do not affect
MIDI events that you create or record after editing the transposition events.