+<!ENTITY url.sru.searchretrieve "http://www.loc.gov/standards/sru/sru-spec.html">
+<!ENTITY url.zeerex.explain "http://explain.z3950.org/">
+<!ENTITY url.sru.explain "http://www.loc.gov/standards/sru/explain/">
+<!ENTITY url.sru.scan "http://www.loc.gov/standards/sru/scan/">
+<!ENTITY url.sru.sort "http://www.loc.gov/standards/sru/scan/">
+