Move cursor vertically up ARG lines.
Interactively, vscroll tall lines if `auto-window-vscroll' is enabled.
If there is no character in the target line exactly over the current column,
the cursor is positioned after the character in that line which spans this
column, or at the end of the line if it is not long enough.
If the variable `line-move-visual' is non-nil, this command moves
by display lines. Otherwise, it moves by buffer lines, without
taking variable-width characters or continued lines into account.
The command C-x C-n can be used to create
a semipermanent goal column for this command.
Then instead of trying to move exactly vertically (or as close as possible),
this command moves to the specified goal column (or as close as possible).
The goal column is stored in the variable `goal-column', which is nil
when there is no goal column. Note that setting `goal-column'
overrides `line-move-visual' and causes this command to move by buffer
lines rather than by display lines.
If you are thinking of using this in a Lisp program, consider using
`forward-line' with a negative argument instead. It is usually easier to use and more reliable (no dependence on goal column, etc.).