Vi operators like d, c etc. are usually used in combination with motion commands. It is now possible to use current region as the argument to these operators. (A region is a part of buffer delimited by point and mark.) The key r is used for this purpose. Thus d r will delete the current region. If R is used instead of r the region will first be enlarged so that it will become the smallest region containing the original region and consisting of whole lines. Thus m . d R will have the same effect as d d.