│ [ ] Grouped Undo │
[X] When Grouped Undo is on, Edit│reverses the effects of the previous command and all immediately preceding commands of the same type.
These are "groupable" commands:
■ cursor movements
For example, if you type ABC and Grouped Undo is on, you can choose Undo one time to delete the group ABC.
[ ] When Grouped Undo is off, Edit│Undo reverses the effect of a single editor command or keystroke.
For example, if you type ABC and Grouped Undos is off, you must choose Undo three times to delete the characters: C, then B, then A.
In terms of groups, inserting a carriage return is considered an insertion followed by a cursor movement.