Derwent Patent Citation Index: Missing Citations

rakurt@mmm.com
Fri, 20 Aug 1999 08:02:23 -0500

We too have noticed the same problem to the one Joerg Ohms gives below. I
had hoped that a reply would have been posted by now, but have not seen
anything on the list. Can Derwent please respond? This could be an
important data integrity issue. Thanks

Richard Kurt
3M
rakurt@mmm.com

Joerg Ohms Wrote:
The concept of Derwents Patent Citation Index (DPCI) includes the
documentation of both cited and citing patents. This means that a given
citation should be retrieved within the CITED PATENT SEGMENT of a
younger patent family record and within the the CITING PATENT SEGMENT of
its own patent family record.
The european patent EP 877245 cites the german patent DE 4244082. This
is documented within the CITED PATENT SEGMENT of its own patent family
record (AN 1998-387103). However, this citation is missing within the
patent family record of DE 4244082. The CITING PATENT SEGMENT of this
record simply does not not exsist (AN 1994-218920).
I am wondering how often such missing citations occur within the DPCI
file. Has anyone made similar observations or did we find the only bad
record within the DPCI file?