.Unique_str( str{} )
  {
    extrn       .Unique_number;
    unsigned    num;

    num = ++.Unique_number;
    str{0} = 'a' + (num>>12)&$F;
    str{1} = 'a' + (num>>8 )&$F;
    str{2} = 'a' + (num>>4 )&$F;
    str{3} = 'a' + (num>>0 )&$F;
    str{4} = '*0';
  }
