[OPEN-ILS-GENERAL] 008 field and leader

[Mike Rylander]

On Thu, Jun 23, 2011 at 9:32 AM, Paul Hoffman <paul at flo.org> wrote:
> Mieke,
>
> On Thu, Jun 23, 2011 at 08:41:56AM -0400, Mieke Stroo wrote:
>> The positions 0-4 and 12-16 in the leader are unclear to us. According
>> to the MARC 21 standard this information should be computer generated.
>> Is it alright to use a set number (00620) for the positions 0-4 and
>> leave the positions 12-16 open?
>
> A MARC record consists of three parts: leader, directory, and field
> contents.  Leader/0-4 encode the length (in bytes) of the whole record,
> and leader/12-16 encodes the offset (in bytes) from the beginning of the
> record to the beginning of the field contents -- in other words, the
> length of the leader plus the length of the directory.  So they have to
> be exactly right, which is why they're computer generated.  I don't know
> enough about EG to know if it will tolerate incorrect values, but I
> doubt it.
>

Evergreen only deals with MARC in XML format, so the leader's length
bytes are of no use.  Upon export in binary MARC, the leader is
appropriately adjusted.  So, in fact, Evergreen tolerates incorrect
(or more correctly, useless) data there, since it doesn't mean
anything in XML.

-- 
Mike Rylander
 | VP, Research and Design
 | Equinox Software, Inc. / Your Library's Guide to Open Source
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