the 11 is probably either 41 or 44. MA1907 is generally accepted to mean Made in Australia, Pattern 1907. It would be a Lithgow bayonet.
the large OA and X means the bayonet was actually manufactured at Orange, a Lithgow subcontractor, and X means it passed the "bending" acceptance test.
mangrovite was a leather subcontractor from 1941 through at least 1945. Most australian WW2 leather scabbards are so marked, with 1944 being the manufacture date on your piece.