MARC21       774     Constituent unit entry [NEW]
  Subfields: 
             $a   Main entry heading
             $b   Edition
             $c   Qualifying information
             $d   Place, publisher, and date of publication
             $g   Relationship information (R)
             $h   Physical description of source
             $i   Display text
             $k   Series data for related item (R)
             $m   Material-specific details
             $n   Note (R)
             $o   Other item identifier
             $r   Report number
             $s   Uniform title
             $t   Title
             $u   Standard Technical Report Number
             $w   Record control number (R)
             $x   International Standard Serial Number
             $y   CODEN designation
             $z   International Standard Book Number (R)
             $6   Linkage
             $7   Control subfieldord (see 772)

 Indic/etc.: 1st: Note controller
             0 Display note
             1 Do not display note
             2nd: Undefined; contains a blank (#)