Facebook doesn’t allow typing LRM and RLM characters in the status field. These are the Unicode characters “Left-to-right marker” and “Right-to-left marker”. People who type in right-to-left languages such as Arabic, Persian, Urdu or Hebrew need these characters to make their status updates appear properly aligned. If i try to type any of these characters, they are deleted when i save the message. There is no reason to do this. Facebook engineers, please allow your users to use these characters. Thank you.
Aharoni in Unicode 