Function RevPosFrom(SubS:String;StIn:String;FarIn:Byte):Byte;

    This function is similar  to  PosFrom  except  that  it searches from
    the back of the string (in  reverse).   That is, it starts looking at
    offset FarIn for SubS  and  then  works  its  way toward the front of
    the string.

    Examples

    RevPosFrom('D','ABCDEF',3) = 0

    The function searches  from  position  3  (the 'C') and then works in
    reverse (toward the front  of  the  string)  and thus never finds the
    'D'.

    RevPosFrom('Hi','Hi There',2) = 1

    The  function  starts  searching  from  position  2  and  because  it
    searches in reverse, it finds the 'Hi' at position 1.