Apple Logic Pro 9 - Manual (Page 409)

To divide a region into several portions with the same length
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Hold down the Option key while cutting a region with the Scissors tool.
A plus symbol appears next to the Scissors tool, and the help tag shows Divide Multiple.
The selected region is cut into several pieces—each the same length as the first segment.
For example, to divide a 16-bar region into eight 2-bar regions, cut the region at the start
of bar 3, while holding down the Option key.
To divide regions at the locator positions
1 Set the left and right locator positions where you want them.
2 Select the regions you want to divide within the locator boundaries.
3 Choose Region > Split > Split Regions by Locators (or use the Split Regions/Events by
Locators or Marquee Selection key command).
409 Chapter 13 Creating Your Arrangement