When performing a tagged block MOVE or COPY with option insert off (i-), the moved text will simply overlay any existing text. If option insert is on (i+) then the text will be inserted before the cursor. This can add considerable convenience. For example you may move the block of "C"s in front of the block of "D"s by tagging it, enabling option insert, and performing a move to the first character of the first line of "D"s. You should tag extra spaces to the right so the columns line up. After the move, delete the extra block of "C"s. It is recommended that you always check the state of option insert when performing a tagged block move.