You can select and edit parts of one or more regions, using the Marquee tool or the marquee stripe:
Marquee tool: Use to select and edit region parts (parts of audio and MIDI regions) by dragging across them; looks like a crosshair
Marquee stripe: A thin stripe shown at the top of the ruler
Only the part of the region inside the marquee is selected, letting you select inside, or across portions of, regions. You can perform most edits, such as moving, cutting, copying, and deleting, in the selected area. After editing, the selected area becomes a new, separate region. The marquee selection uses the current Tracks area Snap value.
If you play a project after making a marquee selection, playback starts at the left edge of the selection, and ends at the right edge. If you create a marquee selection while the project is playing, playback continues past the end of the selection.
If you start recording after making a marquee selection, Autopunch mode is activated, and the marquee selection is replaced by the punch locators. All tracks within the marquee selection are record-enabled, and all other tracks are record-disabled.
Select the Marquee tool, then drag in the Tracks area to select parts of one or more regions.
Choose View > Marquee Ruler from the Tracks area menu bar.
Drag in the thin marquee stripe area of the ruler to select parts of one or more regions (also shown on selected tracks).
Shift-click the track headers of the tracks you want to add or remove.
Do one of the following:
Using the Marquee tool:
Press and hold Shift, then click in the Tracks area to change the selection in any direction.
Shift-click inside a selection to move the selection end closest to the pointer.
Option-Shift-click inside a selection to move the selection end farther from the pointer.
Using any marquee selection:
Press and hold Shift while using the Left Arrow key or Right Arrow key to move the marquee start point.
You can also use the Toggle Previous (or Next) Region/Event, or set Marquee Start to Previous (or Next) Transient key commands.
Use the Left Arrow key or Right Arrow key to change the selection end points.
You can also use the Select Previous (or Next) Region/Event, or set Marquee End to Previous (or Next) Transient key commands, depending on the type of region selected.
Do one of the following:
Press Shift–Home (the default Select First, or Shift Marquee Selection Left key command).
Press Shift–End (the default Select Last, or Shift Marquee Selection Right key command).
Press and hold Control and Shift while making the selection.
This action snaps the selection to ticks or samples when editing MIDI or audio regions, depending on the current zoom level. See Snap items to the grid.
Press and hold Control while making the selection.
This action snaps items to the current division value when editing MIDI or audio regions, depending on the current zoom level. See Snap items to the grid.
Control-click the marquee stripe, then choose Set Locators by Regions/Events/Marquee from the shortcut menu.
This action sets the locators to the marquee selection boundaries, rather than the whole region.
Control-click the marquee stripe, then choose Split Regions/Events at Locators or Marquee Selection from the shortcut menu.
When you edit automation data that is spanned by a marquee selection, two automation points are automatically created at the left edge, and two at the right edge, of the selection. This lets you quickly define and create automation data by converting the marquee selection into automation points.