GO_REF URI prefix?

Does anyone know what the URI prefix is for GO_REF? And no,
http://www.geneontology.org/cgi-bin/references.cgi doesn't count. :-)

Thanks,
Jim
-- 
Jim McCusker
Programmer Analyst
Krauthammer Lab, Pathology Informatics
Yale School of Medicine
james.mccusker@yale.edu | (203) 785-4436
http://krauthammerlab.med.yale.edu

PhD Student
Tetherless World Constellation
Rensselaer Polytechnic Institute
mccusj@cs.rpi.edu
http://tw.rpi.edu