amount lines from the top of the scroll region. The remaining lines to the bottom margin are shifted up and space from the bottom margin up is filled with empty lines.
amount = 0 adjust it to 1.
In left and right margin mode the margins are respected; lines are only scrolled in the scroll region.
If the cell movement splits a multi cell character that character is cleared, by replacing it by spaces, keeping its current attributes.
The new lines are created according to the current SGR state
Does not change the (absolute) cursor position.
amount = 0 does not adjust it to 1.