Apple Logic Express 8 - Manual (Page 507)

Chapter 20 Editing MIDI Events in the Transform Window 507
Some Points to Note About the Map
The map is only visible when chosen in one of the Operations pop-up menus.
Appropriate selection conditions must also be set, or the map will not be shown.
The map is universal, which means that it remaps one MIDI value to another.
It does not know what type of MIDI data is sent to it. It is only concerned with the value
of the data.
This means that one map can be used to simultaneously alter the pitch, velocity, and
length values of incoming note events, for example.
Exchanging Parameter Values
You can re-route the value of each of the three event parameters: Channel, Data
Byte 1, and Data Byte 2 to the value of a different parameter from this group.
To replace the source (Condition value) with the target parameter value:
m Click the dots on the lines between the Selection Conditions and Operations areas.
Repeated clicks will cycle between different targets.
Note: The value is exchanged before the operation is performed.