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Authority record directory elements

Find details about the elements of the authority record directory.

The record directory consists of a series of fixed-length entries containing the tag, length, and starting character position of each control and variable field in the record. A field terminator ends the record directory. Each entry is 12 bytes.  

The starting position is expressed as the byte offset from the first character following the record directory field terminator.

In OCLC-MARC Records, any element, value, field, subfield, etc., marked obsolete is no longer valid. Current records will not contain these invalid codes. However, previously exported records may contain obsolete MARC coding.

Ind = Indicator  |  SFC = Subfield code  |  R = Repeatable  |  NR = Nonrepeatable  |  Blank = Blank

Bytes 00-11

Byte Definition


  • Number of characters associated with the field
  • Always = 3 numeric characters
  • Right-justified with leading zeros
  • Values range from 001 to 999

Field Length

  • Number of characters in the field identified by the tag: indicators, subfield codes, data, and a field terminator
  • Always = 4 numeric characters
  • Right-justified with leading zeros

Starting Character Position

  • Starting character position of the variable field to which the entry corresponds
  • Relative to the Base address given in bytes 12–16 of the record leader    Always = 5 numeric characters
  • Right-justified with leading zeros
  • Starting character position of first field = 00000


Tag                 Field Length                         Starting Character Position

001             0013                                 00000

005            0016                                 00018

100             0040                                00075