[Web4lib] Conversion between ISBN-10 and ISBN-13

[Paul F. Schaffner]

>> This still doesn't make sense to me.   Since ISBNs are assigned by the
>> publishers to books, why would there be any conversion of 10 digit
>> numbers to 13 digits?  The books are already published.  Why not just
>> assign 13 digit numbers after a certain date and leave it at that?

As I understand it, many books have been and will continue to be
assigned both 10s and 13s (and many more have been assigned 10s
and "bookland EANs," which are the same as 13s), so every system
has to assume that any book with an ISBN may also have an ISBN alias.

>>  Why convert 10 to 13 digit?  Can't systems simply handle both?

Systems should indeed handle both. In particular, they should be
able to retrieve the appropriate record even if the record contains
only the 10 and the query contains a 13, or vice versa. This is
obviously especially important for automated batch processes,
such as 'enhancement' (links to dust-jacket images, etc., via ISBN),
or record overlay, or many acquisition processes. I think most people
using commercial systems will not need to do anything: the systems
will be upgraded to support on-the-fly transparent query filtering
and smart matching. But some people build their own systems, or are stuck 
with obsolete or unsupported systems, and they will have to find a way to 
achieve the same results, e.g. by doing batch conversions on the records
(to make sure that every record with a 10 also contains a 13, and
every record with a 978- 13 also contains a 10), or by building
their own query-converter, or some combination of these.

(All of this is slightly complicated by OCLC's practice this
past year of putting 13s in the 024/3 field rather than in the
020: to retrieve the records that you've downloaded from OCLC
this year and added to your system, either your LMS will have to
know to look in both 020 and 024/3 for an ISBN search, or
you'll have to change your records (to add a 13-digit 020), or
again the query will need to be filtered on the fly.)

pfs
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Paul Schaffner | pfs at umich.edu | htpp://www-personal.umich.edu/~pfs/
Head of e-text production, Univ.of Michigan Digital Library Prod. Svc.
Head of tech services, Jackson (Michigan) Community College Library
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