the split/demix functions in Logic are really useful IMHO.
Here's an outline:
[b]Region > Split/Demix > Split regions by locators[/b]
If you want to split all selected regions between say Bar 2 and 3, set the locators to 2 1 1 1 and 3 1 1 1 respectively. The cycle can be enabled or disabled - all regions will be cut at these two points:
As you can see this is a quick way to split longer region(s) in two places to create a new region.
A quick way to do this is holding the CMD key and dragging a Cycle in the Bar Ruler!
[b]Region > Split/Demix > Split regions by playhead[/b]
Same as above, except the position of the Playhead decides where all selected regions will be cut once.
[b]Region > Split/Demix > Demix by event channel[/b]
Logic splits any selected MIDI regions which contain different MIDI event Channels. Basically, a separate MIDI region is created for each MIDI channel that is found.
[b]Region > Split/Demix > Demix by note pitch[/b]
This is great for drums, where each pitch/note denotes a different sample/sound.
Logic looks at all the selected MIDI regions and creates new MIDI regions for each pitch that is found.
The picture above shows a MIDI region that has been pitch demixed into 5 separate regions on 5 tracks assigned to the same channel strip.
This makes it very easy to quickly mute, solo, transform and quantize a single pitch (e.g. kick, snare etc) from the Arrange area!
Hope that helps,