Example file

https://drive.google.com/file/d/1Q8IKiAA66opGsu_xlxRjkhT7ykpKFPww/view?usp=drivesdk

Front and back is the same as left and right with a chain of bones, just depends on the way it is being viewed. r and l labels will apply symmetry if the front and back actors are named such internally. Note joint order.