Established heading records for topical terms typically include several 4XX and 5XX fields.  The tracing fields are justified by numerous 670 (Source Data Found) fields.  Sources in which no information was found are recorded in a single 675 field, each identified by subfield $a.  The 675 field is not repeatable.

In this record, 008/06 is coded i to indicate that the heading can be geographically subdivided by the indirect method.  The descriptive cataloging rules code in 008/10 is n, because this character position is not applicable to the formulation of topical term headings.

LDR       * * * * *nz###22* * * * *n##4500

001       <control number>

003       <control number identifier>

005       19860808072450.5

008       

010  ##  $aex#86004405#

040  ##  $a<organization code>$c<organization code>

150  ##  $aOptical disks

450  ##  $aDiscs, Optical

450  ##  $aDisks, Optical

450  ##  $aOptical discs

450  ##  $aLaser discs

450  ##  $aLaser disks

450  ##  $aLaserdiscs

450  ##  $aLaserdisks

550  ##  $wg$aOptical storage devices

670  ##  $aWork cat.: McQueen, J. Videodisc and optical digital disk technologies and their applications in libraries, 1986.

670  ##  $aWeb. 3$b(disk or disc)

670  ##  $aLibrary Literature$b(Laser discs x Optical discs)

670  ##  $aMcGraw-Hill dict. sci. tech.$b(optical disk - a type of video disk storage device consisting of a pressed disk with a spiral groove at the bottom of which are submicrometer-sized depressions that are sensed by a laser beam.)

670  ##  $aLCIB thes.$b(Optical disks, see Optical storage devices)

670  ##  $aPrice, J. "The optical disk pilot program at the Library of Congress." Videodisc and optical disk: v. 4, Nov.-Dec. 1984: p. 424-432.

670  ##  $aO'Neill, S. "Optical disk technology." LC science tracer bullet TB 84-6.

670  ##  $aBPI$b(Optical disks, see Optical storage devices)

670  ##  $aRandom House$b(Optical disk; Optical disc; also called Laser disk)

670  ##  $aHennepin$b(Optical discs x Laser discs)

675  ##  $aNCC thes. comput. terms;$aNASA;$aIAD;$aNCC thes. comput. terms;$aBDNE2

See also:

Appendix B:  Full Record Examples

Appendices