M (move) Command

M[number-of-lines]: Use the M (move) command to move a line or block of lines. The B (before) or A (after) line commands are used to specify the destination of the lines to be moved. No other commands can be entered on the lines to be moved.
number-of-lines: Specifies the number of lines to be moved. The default is 1.
M: Specifies a single line to be moved.
Mn: Specifies the first of n lines to be moved.
MM...MM: Specifies the first and last lines of a block.

Rules for Using the Move Line Command

When using the M number-of-lines or the MM form of the command, you cannot enter any other commands on the lines being moved.

Each MM must be paired with another MM.
You must pair a B (before) or an A (after) line command with every M or pair of MM commands.