Or use your decimal as a place extension instead of a hierarchal separator. Your tree would look like this: 1 11 12 1.0 2 21 Then you just ensure

Or use your decimal as a place extension instead of a hierarchal separator. Your tree would look like this: 1 11 12 1.0 2 21 Then you just ensure that '.' sorts after all digits. (Probably by using a different symbol.) Basically, the '.' means "insert after."