The rules covering the specific type of material--electronic resource–are given in AACR2 chapter 9 and those addressing the serial aspects are given in chapter 12.  Choice of MARC format has differed through the years.  Prior to the final phase of format integration in March 1996, electronic serials could be cataloged using either a serial or a computer file fixed field (i.e., 008).  CONSER policy however required that serial electronic resources be cataloged using the serials format so that the records could be authenticated.  With the full implementation of format integration, all electronic serials were cataloged using leader code "m", a computer file 008, and a serial 006:  existing CONSER records were converted to this format in OCLC.  In June 1997, MARBI redefined leader code "m" to limit its usage and the new definition was implemented in OCLC in March 1998.  The limited use of leader/06 code "m" has meant that most electronic resource serials are coded "a" for "language material" and include a serial 008 field and an electronic resource 006 field.  OCLC is converting CONSER records for electronic resource serials back to leader/06 code "a" with a corresponding serial 008 field and an electronic resource 006 field.  For further details on fixed field construction, see the CONSER Editing Guide ( Fixed Length Fields - General Information ).  Field 007 is also used for serial electronic resources.

See also:

Module 30.  Direct Access Electronic Serials