Broke down the symbol in 1 into a single part, this part move along two diagonals the one following (1-5-9) and the one following (1-6-8).
Now broke down the sybol in two into two different part, on consisting of the line at the top and the one at the bottom of the rectangle, and another one consisting of the line at the sides of said rectangle.
You move the up and down component along the diagonal (2-6-7) and the one with the sides along (2-4-9).
Finnaly the figure in 3 can be broken down into two as well, one line at the top of the symbol and another one looking like the one in 1 turned upside down.
You move the line along (3-5-7) and the other component along (3-4-8).
Every time two component fall in the same case they merge with each other to create a new one.
9 is the merging of the sides of the rectangle and the the symbol in 1, wich gives a M (D).>>10978493>>10978448
Please don't tell me I wrote this explanation for nothing, because it doesn't look like the pattern in >>10977941
but rather the one in >>10978375