def yoToZA( yo_i ) :
    """Returns ZA designator, or special code, from yo id.  That is, ::
      yo_i = 0, 1,    2,    3,    4,    5,    6, 7,  8,  9,  10, 11,   12,   13,   14,   15,   16
      is converted to
             0, 1, 1001, 1002, 1003, 2003, 2004, 0, -8, -9, -10,  1, 1001, 1002, 1003, 2003, 2004
    with the following meanings ::
          none, n,    p,    d,    t,  He3,   He, g, b+, b-,  EC,  n,    p,    d,    t,  He3,   He.
    yo_i must be a python integer."""

    if ( yo_i < 0 ) or ( yo_i > 16 ) : raise Exception( "\nError in yoToZA: unsupported yo value = %s" % repr(yo_i) )
    yo = yo_i
    if ( yo > 10 ) : yo -= 10
    return ( 0, 1, 1001, 1002, 1003, 2003, 2004, 0, -8, -9, -10 )[yo]