<Undo> or *undo* *<Undo>* *u*
u Undo [count] changes. {Vi: only one level}
*:u* *:un* *:undo*
:u[ndo] Undo one change. {Vi: only one level}
*CTRL-R*
CTRL-R Redo [count] changes which were undone. {Vi: redraw screen}
*:red* *:redo* *redo*
:red[o] Redo one change which was undone. {Vi: no redo}
*U*
U Undo all latest changes on one line. {Vi: while not
moved off of it}