Apple Aperture - Manual (Page 186)

186 Part II Photo Editing
Keyboard Shortcuts for Working with Stacks
Aperture provides the following keyboard shortcuts for efficiently working with stacks:
Keyboard shortcut Function
Go to previous stack
Go to next stack
Open/Close stack
Open all stacks
Close all stacks
Create stack
Unstack
Split stack
Set stack pick
Promote stack item
Demote stack item
Extract item
page
up option
page
down option
shift K
option
'
option ;
K
shift K
option K
[
]
shift option K