bottomrow= see description
rightcolumn= see description
Clears a rectangular area with the space character.
If cursor origin mode is set the rectangle is interpreted relative to the top left of the current scroll region. Otherwise it's relative to the top left of the terminal.
rightcolumn default to their bottom-most/right-most valid values.
If cursor origin mode is set and the rectangle exceeds the current scroll region it's clipped to the current scroll region. Otherwise the rectangle is clipped to the full terminal.
rightcolumn this sequence does nothing.
The colors of the cleared cells are not changed.
The other attributes of the cells are reset.
If filling the cells splits a multi cell character that character cleared, by replacing it by spaces, keeping its current attributes.
When only some of the lines have set set double width line, the region this sequence acts upon might not look rectangular in to the user on display.