Applies to Matrix and Pathway key projects
Some types of edits to a key (such as adding or deleting items in the trees, scoring and changing feature types) may be undone 
by pressing Ctrl-Z or choosing Undo from the Edit menu
The following operations may be undone:
- Add Item
- Delete Item
- Rename Item
- Change Item Type (e.g. Feature/State)
- Change Feature Type (Grouping/Multistate/Numeric)
- Cut
- Paste
- Drag and Drop
- Set Score
- Clear Score
The undo history is limited to 200 edits. As additional edits are performed the undo edits at the tail of the queue are removed.
The following operations reset the undo history:
- New Key
- Open Key
- Open Recent Key
- Import Key (LIF/LIF3)
- Import Item Lists (Feature/Entity)
Any changes made prior to performing these operations cannot be undone or redone.
Operations undone using Ctrl-Z may be redone by pressing Ctrl-Shift-Z or choosing Redo 
from the Edit menu.