add an empty line at the begin of a rectangle

[Rainer Stengele]

Hi,

I believe a simple question but I cannot find a solution:

I want to add an empty line at the begin of a rectangle and thus shift the 
while rest of only that column in the buffer down by 1 row.
Example:

Having:

AAAA 0000
BBBB 1111
CCCC 2222
     3333

I want to get:

     0000
AAAA 1111
BBBB 2222
CCCC 3333

Thank you.
Regards, Rainer