400. That’s an error.

Google cannot redirect you to http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1=20020104101.PGNR. because the request was invalid.

This might be because the link was created a long time ago. Try your search again on Google. That’s all we know.