specifies the number
of lines of text to move. Follow the n argument with a space. Without the n argument, only the line of text that contains the line command is
moved.
A
marks the target position
of the line of text to be moved; in this case, after the line where
the A argument is typed. You can place the A argument either before
or after the line to be moved.
B
marks the target position
of the line of text to be moved; in this case, before the line where
the B argument is typed. You can place the B argument either before
or after the line to be moved.
Details
The M command moves
a designated line of text to a new position anywhere in a window.