LON-CAPA Export to NSDL OAI Archive korte@lon-capa.org loncapansdlexport 500 data no [^\.]+\.[xX][mM][lL]$ oai_dc http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd