Most MARC utilities like MARC::Record depend upon the actual directory lengths 
and having well formed structure.  Isn't that what standards are for?  But 
sometimes you really do get badly formed MARC records and need to recover the 
data.  The presented code does have two caveats, which I pointed out and Ed 
reiterates.  The directory *must* be in the same order as the fields.

However, even if the fields are not in the same order as the directory, code 
could be written to take that into account so long as you can make the 
assumption that the start positions for each directory entry give the "nearest" 
position to the data.  If we take the directory and sort on the start position 
field, we will have the directory in the order necessary for extraction by the 
presented code.

Of course, you would probably want to keep track of the original directory and 
the sorted directory order so you can output the MARC record with the fields in 
the same order as the original.  Things are never ideal when you have corrupt 
MARC records...


Andy.

-----Original Message-----
From: Ed Summers [mailto:[EMAIL PROTECTED] 
Sent: Saturday, May 07, 2005 3:11 PM
To: perl4lib@perl.org
Subject: Re: Corrupt MARC records

> I wondered if any of you had run into similar problems, or if you had 
> any thoughts on how to tackle this particular issue.

It's ironic that MARC::Record *used* to do what Andrew suggests: using
split() rather than
than substr() with the actual directory lengths. The reason for the switch was 
just as Andrew pointed out: the order of the tags in the directory is not 
necessarily the order of the field data.

If you need to you could try downloading MARC::Record v1.17 and try using that. 
Or you could roll your own code and cut and paste it everywhere like Andrew ;-)

//Ed

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